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Respiratory Syncytial Virus (RSV) Overview

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Respiratory Syncytial Virus (RSV): The Disease

Respiratory Syncytial Virus (RSV) is a common and highly contagious respiratory virus that produces cold symptoms such as coughing, sneezing, wheezing, decreased appetite, fever and malaise. Most people who become infected with RSV will recover fully within a week or two without treatment.

Young infants and children, older adults, and individuals with immune system disorders and chronic health conditions are at an increased risk of RSV infection and may also be at an elevated risk of developing complications from the illness. Complications of RSV infection include inflammation of the small airways within the lungs (bronchiolitis) and lung infection (pneumonia) and may require hospitalization for supportive care.

On July 17, 2023 the FDA approved the drug nirsevimab under the trade name Beyfortus, a monoclonal antibody, for the prevention of RSV. Though the CDC has determined that it can define nirsevimab as a vaccine for their purposes, nirsevimab is not classified as a vaccine by the FDA, American Medical Association, or the World Health Organization. To learn about nirsevimab, visit NVIC’s RSV Prevention and Treatment page.Click to read more about RSV disease

Respiratory Syncytial Virus (RSV): The Vaccine

Two RSV vaccines are licensed for use in the US by the Food and Drug Administration (FDA). AREXVY by GlaxoSmithKline (GSK) is approved for use in individuals 60 years of age and older and ABRYSVO by Pfizer is approved for individuals 60 years of age and older and for use in pregnant women for the prevention of RSV disease in their newborns. Neither vaccine demonstrates the ability to prevent transmission of RSV. AREXVY RSV vaccine efficacy peaks within two months of administration, and offers no protection at one year. A booster dose of AREXVY given one year later does not offer any additional benefit.

ABRYSVO RSV vaccine is assumed to offer persistent protection for 7 months but is no longer effective by 24 months. The CDC recommends use of RSV vaccines in all persons 60 years and older, based on “shared clinical decision-making”. This recommendation means that eligible individuals may choose to receive the vaccine if they believe that the benefits of vaccination outweigh the risks. RSV vaccines are also recommended for pregnant women, between 32- and 36-weeks’ gestation during the season when RSV is actively circulating. Click to read more about RSV vaccine

Respiratory Syncytial Virus (RSV) Quick Facts

Respiratory Syncytial Virus (RSV)

The virus is contagious and is transmitted through coughing and sneezing, by coming into direct contact with the virus, and by touching a surface that contains the virus and then touching your face. Young infants, children, older adults, and individuals with immune disorders and underlying chronic health conditions are more at risk of developing RSV infection and suffering from complications of the illness. By two years of age, most infants and children will have had RSV; however, it is possible to have more than one infection throughout a lifetime.

Most individuals who develop an RSV infection will recover fully within one to two weeks without treatment. There are no specific treatments for RSV infection and symptoms can be treated with over-the-counter pain and fever medication, rest, and adequate hydration. Two monoclonal antibodies, Beyfortus (nirsevimab-alip) and Synergis (palivizumab), have been approved for use by the FDA for the prevention of RSV illness in infants and young children up to two years of age. These drugs, however, are not approved for the treatment of RSV infection. Click to read more Quick Facts

Respiratory Syncytial Virus (RSV) Vaccine

In clinical trials for both ABRYSVO and AREXVY, a higher rate of Guillain-Barre Syndrome (GBS), a rare but serious neurological disorder that causes inflammation of the peripheral nerves, was reported among individuals who received the vaccine. There was also a higher rate of atrial fibrillation, a serious heart disorder that may lead to complications such as stroke, heart attack, or heart failure, among vaccine recipients.

In clinical trials, pregnant women who received ABRYSVO had higher rates of preterm deliveries, as well as higher rates of pre-eclampsia (complication of pregnancy with symptoms that include high blood pressure, swelling of the hands and feet, and protein in the urine and gestational hypertension). Click to read more Quick Facts

NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents below, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

What is Respiratory Syncytial Virus (RSV)?

Respiratory Syncytial Virus (RSV) is a highly contagious virus with symptoms of illness that include decreased appetite, coughing, sneezing, runny nose, wheezing, and fever that generally occur within four to six days after infection. Newborns and young infants may present only with symptoms of breathing problems, irritability, and decreased appetite. Infants and young children, as well as older adults, are considered most susceptible to RSV infection.¹

RSV is an enveloped virus belonging to the genus Pneumovirus, family Paramyxoviridae. It contains 11 proteins that are encoded by the non-segmented RSV genome. As a result of being non-segmented, the virus is unable to shift antigenically to cause significant pandemics. While new genotypes of RSV can occur, the older types do not disappear, allowing for both old and new types to circulate simultaneously for long periods of time.²

There are two different subgroups of RSV, A and B, with subgroup A thought to be slightly more virulent than B. The two groups are defined by the reaction of the major surface proteins, with the G protein of the virus helping to attach to the cells of the airway and the F protein assisting by entering the cells of the infected individual.³ Both RSV A and B can circulate at the same time, however, one subgroup usually predominates.⁴

Most RSV infections resolve within one to two weeks without treatment, although complications such as pneumonia or bronchiolitis can occur, resulting in hospitalization. By two years of age, most infants and children will have had RSV,⁵ however, it is possible to have more than one infection throughout a lifetime.⁶ Most adults who become infected will have symptoms of respiratory illness that include cold-like symptoms such as cough, runny nose, sore throat, fever, and general discomfort.⁷

RSV generally begins to circulate in the fall and peaks during the winter months in the U.S. and countries with similar climates; however, seasonality can change in communities from year to year.⁸

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

Is Respiratory Syncytial Virus (RSV) Contagious?

Respiratory Syncytial Virus (RSV) is contagious and is transmitted from person to person. It is spread by coughing, sneezing, or by direct contact with the virus. A person can become infected by coming into contact with the respiratory secretions of an infected individual, usually through coughing or sneezing, or by touching the virus directly (ie kissing). It is also possible to become infected by the virus by touching contaminated surfaces and then touching the face.

Most infected individuals are usually contagious for between three to eight days, although some people can transmit the virus to others for up to two days before symptoms begin. Immunocompromised individuals may be contagious for up to one month.

What is the History of Respiratory Syncytial Virus (RSV) infection in the U.S. and other countries?

Respiratory Syncytial Virus (RSV) was initially identified in 1955 by JA Morris in laboratory chimpanzees housed at Walter Reed Army Institute of Research in Maryland.¹ The chimpanzees, which were used in polio vaccine research, exhibited symptoms of respiratory illness.² Morris was able to confirm that the viral agent, which was initially named Chimpanzee Coryza Agent (CCA), was contagious when he exposed a second group of chimpanzees to the infection.³

In February 1956, a laboratory worker was purposely exposed to the infected chimpanzees and developed symptoms that included a low-grade fever, runny nose, cough, and headache. The lab worker initially tested negative for antibodies, but positive two weeks later. Additionally, blood samples taken from young adults living near Walter Reed Army Medical Center but most infants and children were negative. Antibodies, however, were detected in young adults, of which eight were dwelling in the same army barracks as the initial laboratory worker.⁴

Robert Chanock, a pediatrician and virologist, from Johns Hopkins University began research to isolate a novel pathogen believed to be causing severe respiratory illness in infants While researching, Chanock discovered two additional agents in babies with croup and pneumonia that were identical to CCA.⁵ Johns Hopkins is located within a 30-mile radius of Walter Reed Army Institute, where CCA was initially identified.

Due to the similarity of the novel pathogens to CCA and its characteristics, Chanock suggested the virus be renamed “Respiratory Syncytial” virus.⁶ In 1960, the virus was found in over 50 percent of the young babies diagnosed with pneumonia or bronchiolitis in the Washington D.C. area and in 12 percent of older infants and young children and labeled as a “respiratory pathogen of major significance during early life”.⁷ By the early 1960s, the virus was identified in Australia and attributed to an epidemic of lower respiratory illness in infants.⁸ ⁹

By the early 1980s, RSV was considered the most significant lower respiratory infection in infants and children under the age of two, with most presenting with bronchiolitis and pneumonia. Most outbreaks were reported in the late fall and spring in the U.S. and lasted between two and five months.¹⁰

Public health officials report that between four and five million children develop RSV infection each year, ¹¹ with approximately 2.1 million resulting in outpatient treatment, between 58,000 and 80,000 requiring hospitalization, and between 100 and 300 deaths. Additionally, the virus is estimated to be responsible for between 60,000 and 120,000 hospitalizations and between 6,000 and 10,000 deaths in adults 65 years of age and older.¹²

Prior to 2020, the seasonality of RSV was well established in the U.S., with the season onset ranging from mid-September to mid-November, with the peak from late December to mid-February, and the off-set concluding in mid-May. Since 2020, however, there has been a shift in RSV infection patterns, with the southern U.S. experiencing an increase in cases in the spring and peaking in July. Health officials attribute the change in RSV patterns to disruptions from the COVID-19 pandemic.

Globally, researchers report that in 2019, there were an estimated 33 million lower respiratory infections associated with RSV, 3.6 million RSV hospitalizations, and 26,300 in hospital deaths related to RSV. Additionally, researchers estimated that approximately 101,400 RSV-associated deaths also occurred in children under the age of five years.¹³

Can Respiratory Syncytial Virus (RSV) cause injury or death?

For most people, RSV is similar to the common cold, with symptoms that include coughing, sneezing, wheezing, fever, runny nose, and decreased appetite. In children under the age of six months, RSV symptoms may only include difficulty breathing, decreased appetite, decreased activity, and increased irritability. Most people recover from RSV illness within one to two weeks without treatment.

RSV infection that spreads to the lower respiratory tract can cause complications such as pneumonia or bronchiolitis (inflammation of the small airways of the lung). Symptoms of severe infection may include wheezing, cough, fever, difficulty breathing, and cyanosis (bluish discoloration of the skin caused by lack of oxygen). In infants, severe illness symptoms may include irritability, lethargy, rapid or shallow breathing, poor feeding, cough, and trouble breathing. It is estimated that one to two cases out of 100 require hospitalization, with premature infants and immunocompromised children being at highest risk for severe disease.

RSV complications in adults may include pneumonia or lung infection, and illness may worsen chronic underlying medical conditions such as asthma, congestive heart failure, and chronic obstructive pulmonary disease (COPD). Among adults 65 years of age and older, it is estimated that RSV illness causes 60,000-160,000 hospitalizations and 6,000-10,000 deaths a year.

Who is Most at Risk for Respiratory Syncytial Virus (RSV)?

Young infants and children are considered most at risk for developing Respiratory Syncytial Virus (RSV) infection. RSV is considered the most common cause of acute childhood respiratory illness and the leading cause of hospitalization during infancy.¹ It is estimated that between four and five million children become infected with RSV in the U.S. each year, with an estimated 58,000 to 80,000 resulting in hospitalization.²

More recently, health officials have also determined that RSV can impact older adults, especially those who are frail or who have underlying health conditions.³ The CDC estimates that between 60,000 and 120,000 older adults develop RSV infection that require hospitalization, with 6,000 to 10,000 of those contributing to death.⁴

Individuals with underlying immune diseases, such as those with HIV infection, are also considered to be at a higher risk for developing RSV infection. ⁵

Who is Most at Risk of Complications from Respiratory Syncytial Virus (RSV)?

In infants and young children, those most at risk for developing complications from Respiratory Syncytial Virus (RSV) infection include infants born prematurely, infants younger than six months of age, children with neuromuscular disorders that impact their ability to clear their mucous membranes or swallow properly, and children under the age of two years who have underlying immune disorders, chronic lung disease, or congenital heart problems.

Environmental factors can also cause infants to develop complications from RSV infection. These include a lack of breastfeeding, exposure to tobacco smoke, and poor socioeconomic status. Complications from RSV infection generally occur in countries with limited public health resources and access to supportive treatments and basic care.

Complications of RSV infection in children include inflammation of the small airways within the lungs (bronchiolitis) and lung infection (pneumonia). The CDC estimates that between one and two children out of 100 will require hospitalization for RSV infection, but that most recover fully with supportive care that may include oxygen, mechanical ventilation, and intravenous (IV) fluids.

Adults, especially older adults with underlying health conditions, or who are frail, are at an increased risk of developing complications from RSV infection. This includes adults with chronic lung or heart disease, and those with immune disorders. Complications from RSV infection in this population include pneumonia, and the worsening of chronic illnesses such as asthma, Chronic Obstructive Pulmonary Disease (COPD), and congestive heart failure. In the U.S., it is estimated that between 60,000 and 120,000 RSV infections among older adults require hospitalization, with between 6,000 and 10,000 contributing to death.

Can Respiratory Syncytial Virus (RSV) be prevented and are there treatment options?

Respiratory Syncytial Virus (RSV) can be prevented through common hygiene practices that include:

Frequent and thorough handwashing with soap and water;
Covering sneezes and coughs with a tissue;
Avoiding close contact with others when ill and staying away from individuals who are sick;
Frequent sanitizing of surfaces that are touched often.

There are no specific treatments for RSV infection. Most infants, children, and healthy older adults who become infected will recover within one to two weeks without any medical intervention. The symptoms of RSV infection can be managed with over-the-counter pain and fever medication, fluid and rest.

In cases where breathing problems or dehydration occurs, or if complications such as bronchiolitis or pneumonia develop, hospitalization may be necessary. The CDC estimates that between one and two children out of 100 will require hospitalization for RSV infection, but that most recover fully with supportive care that may include oxygen, mechanical ventilation, and intravenous (IV) fluids. Children and adults who require hospitalization are typically discharged from the hospital within a few days.

Monoclonal Antibodies

Through a joint partnership, AstraZeneca and Sanofi have developed Beyfortus (nirsevimab-alip), a monoclonal antibody, for use in all infants for the prevention of RSV infection. Unlike a vaccine that stimulates the body to produce an immune response against a particular antigen, a monoclonal antibody is given in an effort to stop an infection. This drug received FDA approval for use in all infants up to 24 months of age by the FDA on July 17, 2023. The CDC recommends that all infants under eight months of age born during, or entering their first RSV season (late fall through early spring), receive a single dose of Nirsevimab. Infants and young children ages 8 through 19 months who are considered to be at an elevated risk of severe RSV illness are also recommended to receive a dose during their second RSV season.

Nirsevimab is an extended half-life potent recombinant human kappa monoclonal antibody that targets the prefusion RSV F protein. Company officials report that a single dose of Nirsevimab can offer rapid protection for the entire RSV season.

Findings from the Phase 2/3 study (Melody Study) on the use of Nirsevimab in preterm and high-risk infants reported that the incidence of medically attended RSV-associated lower respiratory illness was 70.1 percent lower in infants who received Nirsevimab versus those who received the placebo through 150 days. The study, however, reported that Nirsevimab had no impact on reducing hospitalization rates.

Twelve infants involved in the Nirsevimab clinical trials died, with two deaths reported from “unknown causes” but believed to be attributed to Sudden Infant Death Syndrome (SIDS). Ten deaths were reportedly linked to “underlying disease” and included cardiac disease, COVID, a tumor, pneumonia, a skull fracture, two from gastroenteritis, and two from unknown causes. The FDA, however, reported that no deaths appeared to be linked to Nirsevimab.

Infants who are considered to be at high risk for RSV can also be administered Synergis (palivizumab) , another monoclonal antibody, to prevent severe complications of RSV infection. This drug is injected intramuscularly (IM), and is recommended by the American Academy of Pediatrics to be given monthly, for five consecutive months, during the fall and winter months, or at any time during the year when RSV infections are similar to the fall and winter months. Palivizumab is not effective as a treatment for an infant experiencing an active RSV infection.

What is Respiratory Syncytial Virus (RSV) Vaccine?

There are two RSV vaccines approved by the U.S. Food and Drug Administration (FDA) for use in the U.S. The CDC recommends that all persons 60 years of age and older consider receiving a single dose of RSV vaccine if they believe that the benefits of the vaccine outweigh the risks.

Pfizer’s ABRYSVO RSV vaccine is FDA approved for use in adults 60 years of age and older for the prevention of lower respiratory tract disease caused by RSV. It is also approved for use in pregnant women for the prevention of RSV illness in their infants. The CDC recommends that all pregnant women between 32- and 36-weeks’ gestation receive a dose of RSV vaccine during the season when RSV is actively circulating.

ABRYSVO is a non-adjuvanted bivalent stabilized prefusion F subunit vaccine that contains 60 mcg each of lyophilized recombinant prefusion F protein from RSV-A and RSV-B subgroups expressed in CHO cells.

Each dose 0.5ml dose also contains 0.11 mg tromethamine, 1.04 mg tromethamine hydrochloride, 22.5 mg mannitol, 11.3 mg sucrose, 0.08 mg polysorbate 80, and 1.1 mg sodium chloride.

ABRYSVO is approved by the FDA to be given as a single dose administered intramuscularly (IM).

GlaxoSmithKline’s AREXVY RSV vaccine is FDA approved for use in adults 60 years and older for the prevention of lower respiratory tract disease caused by RSV. AREXVY is a recombinant stabilized prefusion trimeric F (preF3) protein subunit vaccine. Each 0.5 ml dose contains 120mcg of RSV RSVPreF3 recombinant antigen derived from the RSV fusion surface glycoprotein of an RSV-A strain.

The vaccine also contains the AS01e adjuvant, which is made up from both QS-21 Stimulon and MPL (monophosphyoryl lipid a). QS-21 Stimulon is a purified extract from the bark of the Quillaja saponaria vergreen, or soap bark tree. It is designed to enhance the “turbocharge vaccines by strengthening and broadening immune responses (both T cell and antibody mediated) to a vaccine’s antigens.” MPL is an immune-stimulating fat. After the vaccine is reconstituted, each 0.5 mL dose contains 120 mcg of the recombinant RSVPreF3 antigen, 25 mcg of QS-21 and 25 mcg of MPL. Each dose also contains 4.4 mg of sodium chloride, 0.15 mg of disodium phosphate anhydrous, 0.83 mg of potassium dihydrogen phosphate, 0.26 mg of dipotassium phosphate, 14.7 mg of Trehalose, 0.18 mg of polysorbate 80, 0.5 mg of DOPC, and 0.125 mg of cholesterol. Each dose of the vaccine may also contain residual amounts of host cell proteins (≤2.0%) and DNA (≤0.80 ng/mg) from the manufacturing process.

AREXVY is approved by the FDA to be given as a single dose administered intramuscularly (IM).

On July 17, 2023 the FDA approved the drug nirsevimab under the trade name Beyfortus, a monoclonal antibody, for the prevention of RSV. Though the CDC has determined that it can define nirsevimab as a vaccine for their purposes, nirsevimab is not classified as a vaccine by the FDA, American Medical Association, or the World Health Organization. To learn about nirsevimab, visit NVIC’s RSV Prevention and Treatment page.

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

What is the history of Respiratory Syncytial Virus (RSV) vaccine in America?

In 1966, the first vaccine for Respiratory Syncytial Virus (RSV), a formalin-inactivated RSV vaccine, was administered to U.S. infants and children participating in four clinical trials. The vaccinated children were subsequently exposed to RSV in the community and those who had no antibodies against RSV infection prior to vaccination experienced more frequent and severe RSV infection, a condition known as enhanced respiratory disease. The affected infants and children presented with wheezing, bronchopneumonia and fever, with approximately 80 percent requiring hospitalization. Additionally, two toddlers who were vaccinated as infants died as a result of their enhanced illness.

As a result of the failed vaccine and harms caused to those who received this experimental vaccine, development of further vaccines to prevent RSV infection stalled for several decades. However, in recent years, several pharmaceutical companies have employed new strategies to develop a vaccine without the risk of enhanced disease.

One approach has been the development of a vaccine to target pregnant women in the hopes that maternal antibodies would be transferred to the infant and offer protection from illness. Strategies has also included the use of novel vaccine technologies such as gene-based vaccines, adjuvanted subunit vaccines, and more. RSV vaccines intended for older adults were also developed and put through clinical trials.

GlaxoSmithKline (GSK) RSV Vaccine

In October 2022, GlaxoSmithKline (GSK) pharmaceutical issued a press release that reported their RSV vaccine reduced severe RSV illness by 94.1 percent in persons 60 years and older. GSK also reported that the vaccine had an overall efficacy of 82.6 percent in their Phase 3 clinical trial. This vaccine combines a recombinant subunit prefusion RSV F glycoprotein antigen (RSVPreF3) with GSK’s proprietary AS01_E adjuvant. This adjuvant is a liposome-based adjuvant that contains two ingredients, 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and saponin QS-21, which stimulates the immune system. This adjuvant is also used in the Shingrix herpes zoster (shingles) vaccine, a vaccine that has been associated with an increased risk of Guillain-Barré syndrome (GBS).

While GSK reported their vaccine to be highly efficacious in reducing severe RSV illness in persons 60 years and older, the clinical trials were not sufficiently powered to estimate its efficacy against hospitalization and/or death. In the clinical trials, there were less than five cases of RSV infection and no associated deaths. Additionally, the clinical trial took place during a shift in the seasonal patterns of RSV infections attributed to the COVID-19 pandemic.

The initial clinical trials for GSK’s RSV vaccine were intended for pregnant women, however, trials were permanently halted due to an undisclosed safety signal with the vaccine product.

During the FDA’s Vaccines and Biologics Products Advisory Committee convened on March 1, 2023 to review GSK’s application for licensure, it was reported that one case of Guillain Barre Syndrome (GBS), a rare neurological disorder that causes inflammation of the peripheral nerves with complications that can include temporary or chronic paralysis, including full body paralysis, and may lead to death, had occurred among the 15,400 clinical trial participants. Additionally, there was a higher rate of vaccine recipients who experienced atrial fibrillation, a serious heart disorder that may lead to complications such as stroke, heart attack, or heart failure, in comparison to those who received the placebo.

GSK also reported that in one clinical trial, Study 007, which studied the use of the experimental RSV shot when given at the same time as the quadrivalent influenza vaccine, of the 442 participants, two cases of Acute Disseminating Encephalomyelitis (ADEM) had occurred, with one case resulting in death.

Despite the safety risks, most committee members voted to recommend the product for licensure. Those who voted against the vaccine expressed concerns regarding the case of GBS, as well as the ADEM safety signal when administered along with the flu vaccine. All committee members, however, voted to recommend the experimental RSV shot based on the vaccine’s effectiveness at preventing RSV acute respiratory illness and lower respiratory tract infection.

On May 3, 2023, the FDA licensed use of GSK’s AREXVY RSV vaccine for use in adults 60 years of age and older. The CDC’s Advisory Committee on Immunization Practices (ACIP) voted on June 21, 2023 to recommend use of the vaccine in all persons 60 years and older, based on “shared clinical decision-making”. This recommendation means that eligible individuals may choose to receive the vaccine if they believe that the benefits of vaccination outweigh the risks.

Pfizer RSV Vaccine

In August 2022, Pfizer issued a press release announcing the success of their Phase 3 clinical trial of a bivalent RSV prefusion F vaccine candidate, RSVpreF, in persons 60 years of age and older. According to Pfizer, this vaccine is comprised of equal amounts of recombinant RSV prefusion F from subgroups A and B, and was reported to be highly efficacious at preventing severe RSV illness. Company official also reported that the vaccine was well tolerated by clinical trial participants, and had no safety issues.

Safety concerns with the vaccine, however, were revealed at the VRBPAC meeting held on February 28, 2023 to review the clinical data submitted by Pfizer. During this meeting, it was reported that two cases of GBS had occurred during the clinical trial, at a rate of approximately 1 in 9,000. Additionally, one clinical trial participant who received the experimental RSV vaccine experienced a delayed allergic reaction, with complications that included shortness of breath, chest pain, and loss of consciousness.

As with the GSK RSV vaccine, there was a higher number of clinical trial participants who experienced atrial fibrillation after receipt of the vaccine when compared to those who got the placebo.

During this meeting, the FDA also revealed that the placebo used in the clinical trial consisted of the excipients used in the RSV vaccine, without the RSV antigens, and not a saline solution.

Despite the safety risks associated with the vaccine, and the lack of data to show that the vaccine would prevent hospitalization and deaths from RSV, especially among individuals most at risk for the illness, most VRBPAC committee members voted in favor of recommending the vaccine. Those who voted against the vaccine expressed concerns regarding both the vaccine’s safety and effectiveness.

In November 2022, Pfizer announced that their bivalent RSV prefusion vaccine candidate RSVpreF or PF-06928316 targeting pregnant women had an 81.8 percent efficacy against severe RSV illness in infants up to three months. This vaccine candidate is reported to produce antibodies that block the F protein of both RSV subgroup A and B to prevent infection. Pfizer’s clinical trial involved the administration of the experimental vaccine to pregnant women in their third trimester with the goal of offering protection to their newborn infants through maternal antibodies. While the vaccine was reported by Pfizer to be highly efficacious, they also acknowledged that the vaccine failed to reduce the number of infant medical appointments for RSV, including visits for non-serious infection.

Clinical trials of Pfizer’s RSV vaccine candidate commenced in June 2020 and was reported to have been conducted in 18 countries in both the northern and southern hemispheres through several RSV seasons. Approximately 7,400 pregnant women under the age of 49 were randomized 1:1 to receive either Pfizer’s RSVpreF vaccine candidate or a placebo at the end of the second trimester or during the third trimester. The women in the study were reportedly followed for safety for six months while their infants were studied for at least one year for efficacy and safety, with some followed for up to two years.

According to data presented by Pfizer during the February 2023 ACIP meeting, 3,682 pregnant women were administered a dose of the experimental RSV vaccine between 24 and 36 weeks gestation, with nearly 14 percent experiencing a vaccine adverse event, 4.2 percent of which were reported as serious, 1.7 percent reported as severe, and 0.5 percent as life-threatening.

Pfizer also reported that 37.1 percent of infants whose mothers received the vaccine were noted to have experienced an adverse event within one month of birth, 15.5 percent of which were considered serious, 4.5 percent as severe, and 1 percent as life-threatening. Pfizer’s data also noted an increased risk of premature and low birth weight for infants born to vaccinated pregnant women. The data also noted the death of one pregnant woman, and 18 fetal deaths (10 in the RSV vaccine group and 8 in the placebo) and 17 infant deaths (5 in the RSV vaccinated and 12 in the placebo group). Pfizer stated that all deaths were unrelated to the vaccine.

While the FDA’s VRBPAC committee voted unanimously in favor of the efficacy of the Pfizer’s ABRYSVO’s RSV vaccine for the prevention of RSV infection in infants whose mothers received the vaccine during pregnancy, four committee members voted against the vaccine as it pertained to the safety data provided by the manufacturer. Those who voted against the use of the vaccine in pregnant women expressed concern over the safety signals found in the clinical trials.

On May 31, 2023, the FDA licensed the ABRYSVO RSV vaccine for use in adults 60 years of age and older, for the prevention of lower respiratory tract disease caused by RSV. This vaccine received a “shared clinical decision-making” recommendation by the CDC’s ACIP on June 21, 2023. A “shared clinical decision-making” recommendation means that individuals 60 years and older may consider receiving a dose of the vaccine if they believe that the potential benefits from the vaccine outweigh the risks.

Pfizer’s ABRYSVO RSV vaccine received FDA approval on August 21, 2023 for use in pregnant women for the prevention of RSV disease in their newborns, to be given between 32- and 36-weeks gestation. In their press release, the FDA acknowledged that pregnant women who received this vaccine experienced higher rates of pre-eclampsia, a serious hypertensive disorder during pregnancy, and pre-term deliveries compared to those who received the placebo. Infants born to vaccinated women had higher rates of jaundice and lower birth weights. The FDA, however, reported that they were requiring Pfizer to complete “postmarketing studies to assess the signal of serious risk of preterm birth and to assess hypertensive disorders of pregnancy, including pre-eclampsia.”

On September 22, 2023, the CDC’s ACIP voted in favor of recommending ABRYSVO RSV vaccine for use in all pregnant women, to be given between 32- and 36-weeks gestation during the season when RSV is actively circulating. The CDC, however, states that pregnant women can decline RSV vaccine if they are planning to have their newborn receive a dose of nirsevimab monoclonal antibody.

In the recommendation for the use the Pfizer RSV vaccine in pregnant women for the prevention of RSV illness in their newborn infants, the CDC’s Advisory Committee on Immunization Practices noted that:

“For the GRADE assessment of harms, results from the phase 2b and phase 3 trials were pooled¶¶ (9,16). The overall evidence certainty using GRADE criteria was rated as very low, driven by the uncertainty in the critical harm outcome of preterm birth (<37 weeks’ gestation).*** ACIP judged the benefits of maternal RSVpreF vaccination at 32–36 weeks’ gestation to outweigh the potential risks for preterm birth and hypertensive disorders of pregnancy.”

GRADE (Grading of Recommendations Assessment, Development and Evaluation) is an evidence-based framework used by the CDC’s ACIP to assess the type or quality of evidence about a vaccine's expected health impacts and the balance of health benefits and risks, along with the values and preferences of persons affected, and health economic analyses.

According to the GRADE system used by the ACIP for evaluating evidence, very low certainty evidence means that confidence in the evidence is lacking and that The true effect is likely to be substantially different from the estimate of effect.

RSV Monoclonal Antibodies

On July 17, 2023 the FDA approved the drug nirsevimab under the trade name Beyfortus, a monoclonal antibody, for the prevention of RSV. Though the CDC has determined that it can define nirsevimab as a vaccine for their purposes, nirsevimab is not classified as a vaccine by the FDA, American Medical Association or the World Health Organization. On August 3, 2023, the CDC recommended that all infants under eight months of age born during, or entering their first RSV season (late fall through early spring, receive a single dose of Nirsevimab. Infants and young children ages 8 through 19 months who are considered to be at an elevated risk of severe RSV illness are also recommended to receive a dose during their second RSV season.

Nirsevimab is not routinely recommended for use in infants whose mothers received a dose of RSV vaccine during pregnancy. However, infants whose mothers received RSV vaccine during pregnancy may be given a dose under certain circumstances, at the discretion of their health care provider. These circumstances include infants born with congenital conditions that place them at high risk for severe RSV illness (congenital health disease, receipt of intensive care services, oxygen supplementation), those who underwent cardiopulmonary bypass, those born to mothers with immunocompromising conditions, and those born within two weeks of maternal RSV vaccination. No safety or effectiveness data exists on the use of Nirsevimab in infants whose mothers received RSV vaccination during pregnancy. To learn about nirsevimab, visit NVIC’s RSV Prevention and Treatment page.

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

Is Respiratory Syncytial Virus (RSV) vaccine effective?

At this time RSV vaccine effectiveness is unknown, as effectiveness is based on real-world data of how the vaccine works in the general population and RSV have just been recently licensed and recommended for use in the general population.

However, vaccine efficacy for RSV vaccines is known and based on ideal situations like well-designed clinical trials. Notably, vaccine efficacy can differ from vaccine effectiveness because a vaccine may not work as well in the real world. Understanding what efficacy and effectiveness mean is also important. Below is an example from Yale Medicine.

An example: Imagine there were 100 people in the vaccine group, and 100 people in the placebo group. If 10 people in the placebo group became infected, but only 2 in the vaccine group got sick, that means the vaccine has reduced the chances of illness by 80%; thus, it is considered to have an efficacy of 80%.

Pfizer’s ABRYSVO RSV Vaccine Efficacy

In the pre-licensing clinical trial, Pfizer reported vaccine efficacy to be 66.7 percent against the first episode of RSV-related lower respiratory tract infection with two or more symptoms, and had 85.7 percent efficacy against the first episode of RSV related lower respiratory tract infection with three or more symptoms. The vaccine, however, was reported to have an efficacy of only 33.3 percent in persons with more than one chronic cardiopulmonary condition. Only two RSV related hospitalizations occurred in the clinical trial, both among placebo recipients. A formal evaluation of the vaccine’s efficacy against severe RSV illness was not conducted due to the small number of cases. No RSV-related deaths were reported among trial participants in both the vaccinated and placebo groups.

Preliminary data also reported ABRYSVO’ efficacy to be 62.1 percent against acute respiratory illness. Pfizer, however, failed to complete the analysis of 25.6 percent of swabs submitted for clinical trial participants with acute respiratory symptoms and as a result, the reported vaccine efficacy may be inaccurate.

There is a lack of data on the vaccine’s efficacy against severe lower respiratory tract infection and in persons with immunocompromising conditions and among individuals considered elderly and frail. Data is also lacking on the vaccine efficacy when administrated with other vaccines.

ABRYSVO pre-licensing clinical trials were conducted during the COVID-19 pandemic when rates of RSV illness had significantly decreased, and result in differences between reported efficacy and effectiveness of the vaccine when in use during a season when RSV is circulating at a higher rate.

This vaccine is assumed to offer persistent protection for 7 months but is no longer effective by 24 months.

RSV Vaccine Efficacy in Preventing RSV in Infants

Pfizer reports that the vaccine efficacy in infants born from mothers who received the RSV vaccine during the third trimester of pregnancy was 57.1 percent at 90 days after birth, but waned to 51.3 percent at 180 days and 41 percent at 360 days. Vaccine efficacy for severe RSV was reported at 81.8 percent at 90 days after birth, but waned to 69.4 percent at 180 days. Vaccine efficacy related to hospitalizations were reported to be 67.7 percent at 90 days after birth, but waned to 33.3 percent at 360 days.

GlaxoSmithKline(GSK) AREXVY RSV Vaccine Efficacy

According to GSK, AREXVY RSV vaccine efficacy was reported to be 82.6 percent against the first occurrence of RSV related lower respiratory tract infection in persons 60 through 79 years of age. Data was not sufficient to determine the efficacy of the vaccine in persons 80 years of age and older. Vaccine efficacy in persons with immunocompromising conditions is also unknown.

Based on available data presented during the February 2023 ACIP meeting, vaccine efficacy for the GSK vaccine peaked at two months post-vaccination and by one year, offered no vaccine acquired protection. Additional data provided by the manufacturer during the June 2023 ACIP meeting showed that giving another dose of the vaccine one year later had no impact on boosting the immune response.

RSV Monoclonal Antibody Efficacy

On July 17, 2023, the FDA approved the drug nirsevimab under the trade name Beyfortus, a monoclonal antibody, for the prevention of RSV in infants and children up to 24 months of age. Though the CDC has determined that it can define nirsevimab as a vaccine for their purposes, nirsevimab is not classified as a vaccine by the FDA, American Medical Association or the World Health Organization. To learn about nirsevimab, visit NVIC’s RSV Prevention and Treatment page.

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

Can Respiratory Syncytial Virus (RSV) vaccine cause injury & death?

At this time data is limited to clinical trial data in healthy individuals, and may not be representative of real world data that has yet to be gathered due the recent rollout of the vaccine’s use in the general population. To learn more about vaccine effectiveness vs. efficacy visit our RSV vaccine effectiveness web page. To learn more about RSV vaccine injuries and deaths, click the links below.

Pfizer’s ABRYSVO RSV Vaccine

During clinical trials for ABRYSVO, in persons 60 years of age and older, the most commonly reported adverse events included swelling, pain, and redness at the injection site, fatigue, headache, muscle and joint pain, nausea, vomiting diarrhea, and fever.

In the first month following vaccination, more people in the vaccine group reported severe adverse events. These severe adverse events included falls, sepsis, congestive obstructive pulmonary disease, and infections/infestations. Study investigators, however, reported that these adverse events were likely not related to vaccination.

Atrial fibrillation, a serious heart disorder, that may lead to complications such as stroke, heart attack, or heart failure, occurred at a higher rate among vaccine recipients than those who received the placebo. While clinical trial investigators reported that the vaccine was not responsible, the FDA has stated that they are continuing to investigate.

Two cases of Guillain Barre Syndrome (GBS), a rare neurological disorder that causes inflammation of the peripheral nerves with complications that can include temporary or chronic paralysis, including full body paralysis, and may lead to death, also occurred during the clinical trial, at a rate of approximately 1 in 9,000. Additionally, one clinical trial participant who received the experimental RSV vaccine experienced a delayed allergic reaction, with complications that included shortness of breath, chest pain, and loss of consciousness.

Pfizer’s clinical trials used a placebo solution containing ingredients that were similar to the vaccine, minus the RSV antigens, rather than using an inert saline placebo.

In clinical trials of the vaccine for use in pregnant women, individuals who received the vaccine experienced higher rates of injection site and systemic reactions than those who received the placebo. The most commonly reported systemic reactions included fatigue, headache, muscle and joint pain, nausea, vomiting, and diarrhea.

Severe or life-threatening adverse events occurring within one month of vaccination were higher among women who received the RSV vaccine, when compared to those who received the placebo (2.2 percent in the vaccine group versus 1.5 percent in the placebo group). Women who received the RSV vaccine were also more likely to experience a non-serious adverse event within one month of vaccination (11.2 percent versus 10. 8 percent).

Women who received the RSV vaccine were more likely to experience premature delivery of their infants when compared to those who received the placebo (5.6 percent versus 4.7 percent). Higher rates of pre-eclampsia and gestational hypertension were noted among vaccine recipients when compared to those who receive the placebo.

“For the GRADE assessment of harms, results from the phase 2b and phase 3 trials were pooled¶¶ (9,16). The overall evidence certainty using GRADE criteria was rated as very low, driven by the uncertainty in the critical harm outcome of preterm birth (<37 weeks’ gestation).*** ACIP judged the benefits of maternal RSVpreF vaccination at 32–36 weeks’ gestation to outweigh the potential risks for preterm birth and hypertensive disorders of pregnancy.”

According to the GRADE system used by the ACIP for evaluating evidence, very low certainty evidence means that confidence in the evidence is lacking and that The true effect is likely to be substantially different from the estimate of effect.

Pfizer’s clinical trial data also reported that 37.1 percent of infants whose mothers received the RSV vaccine experienced an adverse event within one month of birth, with 15.5 percent reported as serious, 4.5 percent as severe, and 1 percent as life-threatening. One woman who received the RSV vaccine died due to complications from post-partum hemorrhage and hypovolemic shock after delivery. Eighteen intrauterine deaths were also reported in clinical trials, with 10 occurring in the vaccine group and 8 in the vaccine group.

GlaxoSmithKline (GSK) AREXVY RSV Vaccine

In pre-licensing clinical trials, the most frequently reported side effect was pain at the injection site. Within four days of receipt of the vaccine, the most commonly reported systemic adverse events included fatigue, myalgia, headache, arthralgia, and fever. Severe systemic adverse events occurred in 3.3 percent of individuals who received the vaccine.

One case of Guillain-Barre Syndrome (GBS) was reported among the 15,400 clinical trial participants. There was also a higher rate of vaccine recipients who experienced atrial fibrillation in comparison to those who received the placebo. Additional serious side effects included Bell’s Palsy, gout, pancytopenia, Graves Disease, and aggravation of psoriasis.

Clinical trials of an experimental RSV vaccine without an adjuvant that contained the same RSVPreF3 antigen as AREXVY conducted in pregnant women found higher rates of pre-term births when compared to those who received a placebo containing sucrose reconstituted with saline (6.81 percent versus 4.95 percent). GSK halted all clinical trials of the vaccine in pregnant women in February 2022 due to an undisclosed safety signal that occurred during the clinical trials.

Sanofi's RSV Monoclonal Antibody Treatment

On July 17, 2023, the FDA approved the drug nirsevimab under the trade name Beyfortus, a monoclonal antibody, for the prevention of RSV in infants and children up to 24 months of age. Though the CDC has determined that it can define nirsevimab as a vaccine for their purposes, nirsevimab is not classified as a vaccine by the FDA, American Medical Association or the World Health Organization. To learn about nirsevimab, visit NVIC’s RSV Prevention and Treatment page.

RSV vaccine adverse events reports submitted to VAERS

According to data released April 26, 2024 by the CDC, 4,567 adverse reactions, including 38 deaths and 286 hospitalizations, have been reported to the Vaccine Adverse Events Reporting System (VAERS). Over 66 percent of adverse events occurred in persons 60 years of age and older.

Even though the National Childhood Vaccine Injury Act of 1986 legally required pediatricians and other vaccine providers to report serious health problems following vaccination to VAERS, many doctors and other medical workers giving vaccines to children and adults fail to report vaccine-related health problem to VAERS. There is evidence to suggest that only between 1 and 10 percent of serious health problems that occur after use of prescription drugs or vaccines in the U.S. are ever reported to federal health officials who are responsible for regulating the safety of drugs and vaccines and issue national vaccine policy recommendations.

Who is at highest risk for complications from Respiratory Syncytial Virus (RSV) vaccine?

Based on the available clinical trial data, pregnant women who received Pfizer’s ABRYSVO RSV vaccine were more likely to experience premature delivery of their infants when compared to those who received the placebo (5.6 percent versus 4.7 percent). Pregnant women also experienced higher rates of pre-eclampsia and gestational hypertension when compared to those who received the placebo.

In clinical trials, infants born to mothers who received ABRYSVO RSV vaccine had higher rates of low birth weight and jaundice when compared to the infants of mothers who received the placebo.

There is no safety data on the use of drug nirsevimab in infants whose mothers received RSV vaccine during pregnancy. To learn about nirsevimab, visit NVIC’s RSV Prevention and Treatment page.

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

Who should not get Respiratory Syncytial Virus (RSV) Vaccine?

According to the package insert for both GSK’s AREXVY and Pfizer’s ABRYSVO RSV vaccine, anyone with a history of severe allergic reaction to any of the ingredients contained in the vaccine should not receive a dose of vaccine.

On July 17, 2023, the FDA approved the drug nirsevimab under the trade name Beyfortus, a monoclonal antibody, for the prevention of RSV in infants and children up to 24 months of age. Though the CDC has determined that it can define nirsevimab as a vaccine for their purposes, nirsevimab is not classified as a vaccine by the FDA, American Medical Association or the World Health Organization. To learn about nirsevimab, visit NVIC’s RSV Prevention and Treatment page.

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

What questions should I ask my doctor about Respiratory Syncytial Virus (RSV) vaccine?

NVIC’s If You Vaccinate, Ask 8! Webpage downloadable brochure suggests asking eight questions before you make a vaccination decision for yourself, or for your child. If you review these questions before your appointment, you will be better prepared to ask your doctor questions. Also make sure that the nurse or doctor gives you the relevant Vaccine Information Statement (VIS) for the vaccine or vaccines you are considering well ahead of time to allow you to review it before you or your child gets vaccinated. Copies of VIS for each vaccine are also available on the CDC's website and there is a link to the VIS for vaccines on NVIC's RSV “Quick Facts” page.

It is also a good idea to read the vaccine manufacturer product insert that can be obtained from your doctor or public health clinic because federal law requires drug companies marketing vaccines to include certain kinds of vaccine benefit, risk and use information in product information inserts that may not be available in other published information. RSV vaccine package inserts are located on NVIC's RSV “Quick Facts” page. To learn about nirsevimab, a monoclonal antibody that is treated as a vaccine by the CDC, visit NVIC’s RSV Prevention and Treatment page.

Other questions that may be useful to discuss with your doctor before getting the RSV vaccine are:

If other vaccines in addition to RSV vaccine are scheduled for me at this office visit, am I allowed to modify the schedule so fewer vaccines are given at once?
What risks are associated with RSV Vaccine?
What should I do if I develop a high fever or appears very ill after vaccination?
What other kinds of reaction symptoms should I call to report after RSV vaccination?
If the RSV vaccine doesn’t protect me, do I have any other options for preventing RSV infection?
What is the frequency and severity of RSV its complications, if I choose not to receive the vaccine?
Why is nirsevimab being treated as a vaccine when it is a monoclonal antibody? What are the risks associated with the drug nirsevimab?

Under the National Childhood Vaccine Injury Act of 1986, doctors and all vaccine providers are legally required to give you vaccine benefit and risk information before vaccination; record serious health problems following vaccination in the permanent medical record; keep a permanent record of all vaccines given, including the manufacturer’s name and lot number; and report serious health problems, injuries and deaths that follow vaccination to VAERS.

Remember, if you choose to vaccinate, always keep a written record of exactly which shots/vaccines you or your child have received, including the manufacturer’s name and vaccine lot number. Write down and describe in detail any serious health problems that develop after vaccination and keep vaccination records in a file you can access easily.

It also is important to be able to recognize a vaccine reaction and seek immediate medical attention if the reaction appears serious, as well as know how to make a vaccine reaction report to federal health officials at the Vaccine Adverse Reporting System (VAERS). NVIC’s Report Vaccine Reactions—It’s the Law webpage can help you file a vaccine reaction report yourself to VAERS if your doctor fails or refuses to make a report.

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

Respiratory Syncytial Virus (RSV) and RSV Vaccine Quick Facts

Respiratory Syncytial Virus (RSV)

Respiratory Syncytial Virus (RSV) is a common respiratory virus with symptoms similar to a mild cold, such as coughing, sneezing, wheezing, decreased appetite, fever, and malaise. The virus is contagious and is transmitted through coughing and sneezing, by coming into direct contact with the virus, and by touching surfaces that contain the virus and then touching your face.
Young infants, children, older adults, and individuals with immune disorders and underlying chronic health diseases are more at risk of developing RSV infection and suffering from complications of the illness. By two years of age, most infants and children will have had RSV, however, it is possible to have more than one infection during an individual’s lifetime.
Most individuals who develop an RSV infection will recover fully within one to two weeks without treatment. There are no specific treatments for RSV infection and symptoms can be treated with over-the-counter pain and fever medication, rest, and adequate hydration. Two monoclonal antibodies, Beyfortus (nirsevimab-alip) and Synergis (palivizumab) , have been approved for use by the FDA for the prevention of RSV illness in infants and young children up to two years of age. These drugs, however, are not approved for the treatment of RSV infection.
Individuals, especially young infants with small airways, may develop complications such as inflammation of the small airways in the lungs (bronchiolitis) or lung infection (pneumonia). Hospitalization may be required for individuals who have breathing problems, or who become dehydrated. Most people who require hospitalization will be discharged within a few days. Infants born prematurely, babies younger than six months of age, and young children with congenital heart and lung disorders, neuromuscular disorders, and those who are immunocompromised are at high risk of developing RSV infection and suffering complications. It is estimated that between four and five million children become infected with RSV in the U.S. each year, with an estimated 58,000 to 80,000 resulting in hospitalization.
Adults with chronic health diseases, older adults, and those with immune disorders are also at risk of developing RSV illness and suffering complications from infection. The CDC estimates that between 60,000 and 120,000 older adults develop RSV infections that require hospitalization, with 6,000 to 10,000 of those contributing to death.

Respiratory Syncytial Virus (RSV) Vaccine

There are two RSV vaccines licensed for use in the US: ABRYSVO, a bivalent unadjuvanted prefusion F subunit vaccine manufactured by Pfizer; and AREXVY, a recombinant stabilized prefusion trimeric F (preF3) protein subunit vaccine, containing the AS01e adjuvant. ABRYSVO is licensed for use in adults 60 years of age and older and in pregnant women, for the prevention of RSV illness in their infants while AREXVY is licensed for use in adults 60 years of age and older. The CDC’s use recommendation is for individuals 60 years of age and older to consider receiving a dose of the vaccine if they believe that the potential benefits from the vaccine outweigh the risks. RSV vaccines are also recommended for pregnant women, between 32- and 36-weeks’ gestation during the season when RSV is actively circulating.
Vaccine complications in vaccine recipients for both vaccines reported during clinical trials was a higher rate of Guillain-Barre Syndrome (GBS), a serious neurological disorder, and atrial fibrillation, a serious heart disorder, that may lead to complications such as stroke, heart attack, or heart failure. Clinical trial data also showed that when AREXVY was given at the same time as the quadrivalent influenza vaccine there was a significantly increased risk of Acute Disseminated Encephalomyelitis (ADEM), a serious and potentially fatal swelling of the brain and spinal cord.
ABRYSVO clinical trial data for vaccinated pregnant women reported higher rates of preterm deliveries, pre-eclampsia, swelling of the hands and feet, protein in the urine, and gestational hypertension) than those who received the placebo.
As of April 26, 2024, there have been 4,567 reports of RSV vaccine reactions, including 38 deaths and 286 hospitalizations. Over 66 percent of adverse events occurred in persons 60 years of age and older.

Food & Drug Administration (FDA)

RSV Vaccines

AREXVY (Respiratory Syncytial Virus Vaccine, Adjuvanted) Package Insert and Licensing Information
ABRYSVO (Respiratory Syncytial Virus Vaccine) Package Insert and Licensing Information

Monoclonal Antibodies

Beyfortus (nirsevimab-alip) Package Insert and Prescribing Information
SYNAGIS® (palivizumab) Package Insert and Prescribing Information

Centers for Disease Control (CDC)

Vaccine Reaction Symptoms & Ingredients

NVIC’s Ask 8, If You Vaccinate webpage contains vaccine reaction symptoms.

Search for Vaccine Reactions

NVIC hosts MedAlerts, a powerful VAERS database search engine. MedAlerts examines symptoms, reactions, vaccines, dates, places, and more.

Reporting a Vaccine Reaction

Since 1982, the NVIC has operated a Vaccine Reaction Registry, which has served as a watchdog on VAERS. Reporting vaccine reactions to VAERS is required by federal law under the National Childhood Vaccine Injury Act of 1986. If your doctor will not report a reaction, you have the right to report a suspected vaccine reaction to VAERS.

Selected NVIC statements & commentaries related to Respiratory Syncytial Virus (RSV) or RSV vaccine

NVIC Newsletter Articles

Wrangham T. Vote to Add Drug to Childhood Vaccination Schedule Opens Door to Daycare Mandates, Tracking, and Injury Liability Shield. Aug. 10, 2023.

Wrangham T, Jolly J. FDA Committee to Vote on New RSV Vaccine Targeting Pregnant Women & Babies. May 3, 2023.

The Vaccine Reaction News Journal

Parpia R. RSV Vaccines for Senior Adults Linked to Guillain-Barré Syndrome. Mar. 11, 2024.

Parpia R. CDC Reports Errors in RSV Vaccines Given to Pregnant Woman, Monoclonal Antibody Shots to Children. Feb. 5, 2024.

Baker A. Twelve Infants Die During Clinical Trials for FDA-Endorsed RSV Drug. June 19, 2023.

Baker A. RSV Vaccine Approved by FDA for Adults 60 and Older. May 29, 2023.

Hobley N. Guillain-Barré Syndrome Linked to the RSV Vaccine. Mar. 14, 2023.

Hobley, N. Pfizer’s New RSV Vaccine for Pregnant Women on Fast Track. Nov. 22, 2022.