Who should not get the Influenza (Flu) vaccines?

Different influenza vaccines are licensed by the FDA and approved for use in different groups of people according to a person’s age, state of health and personal history of allergies or reactions to previous vaccinations. By federal law, pharmaceutical companies producing vaccines for release in the US. must publish information that accompanies vials of vaccine shipped to public health clinics and doctors’ offices that contain information about the vaccine’s ingredients, safety and effectiveness data from pre-licensure clinical trials, contraindications and precautions, reported vaccine adverse events, age use recommendations and more.

Prior to receiving an influenza vaccination or any vaccination, NVIC encourages consumers to read information contained in the vaccine manufacturer package insert carefully.

Note: There are certain influenza vaccines that are licensed for use by people in certain age groups. For example, high-dose flu shots are not licensed for use by people under age 65 years and flu shots administered intradermally are not licensed for use by children under age 18 years. Refer to the specific vaccine’s product insert in Influenza Quick Facts for additional information.

According to most manufacturers’ package inserts for influenza vaccines, children younger than six months of age and people with severe, life-threatening allergies to influenza vaccine or any ingredient in the vaccine should not receive flu shots.

Most influenza vaccine package inserts with the exception of Flucelvax,¹ using Madin Darby canine kidney cells for production, and Flublok,² using armyworm cells for production, list an allergy to egg and egg protein as a contraindication to vaccination because most influenza vaccines are made using chicken eggs. Flublok, however, is the only flu vaccine considered completely egg-free.³

In 2016, the CDC’s Advisory Committee on Immunization Practices (ACIP) revised flu shot recommendations for people with egg allergies and stated that individuals with an allergy to egg can receive any type of flu vaccine, whether manufacturers use chicken eggs for production or not. ⁴ In 2022, CDC officials advised that individuals who develop hives from egg products may be vaccinated without any special precautions, while those who have experienced a severe anaphylactic reaction (one involving respiratory distress, angioedema or use of epinephrine) should be monitored in a setting where there is a health care professional trained to recognize and quickly treat an anaphylactic reaction. While CDC officials stated that allergic reactions could occur in individuals who are allergic to eggs, they considered the reactions to be rare and not serious enough to warrant a contraindication.⁵

In 2023, the CDC dropped all warnings related to egg allergies and declared that no special precautions were necessary to ensure the safe administration of flu shots in egg allergic individuals. According to the CDC, individuals with egg allergies can receive any influenza vaccine indicated for their age and risk category without any added safety measures than those implemented for the administration of other vaccines.⁶

Currently a severe allergy to a vaccine component or a history of a life-threatening allergic reaction to a previous flu shot are the only CDC approved official contraindications (medical reasons for not getting vaccinated) to receiving influenza vaccine. A history of GBS within six weeks of a previous flu vaccine, a severe egg allergy (i.e. respiratory distress, recurrent vomiting, angioedema, lightheadedness, treatment with epinephrine) or “moderate or severe acute illness with or without a fever,” are now only considered precautions to vaccination. According to the CDC, vaccination should be deferred in the presence of a precaution, but persons may receive the vaccine if the benefit of vaccination is believed to outweigh the risk.⁷

Live Nasal Spray Flu Vaccine (FluMist): FluMist is a live virus vaccine and a vaccinated person may potentially shed and transmit the live vaccine strain influenza virus to others.^{8 9} In 2016, the CDC’s Advisory Committee on Immunization Practices (ACIP) recommended against the use of this vaccine when it was found to be ineffective at preventing influenza. ¹⁰ It was, however, approved as an option again for the 2018/2019 flu season without evidence to support that a revised formulation would offer any protection.¹¹ FluMist will be available for use during the 2023/2024 season.

• Individuals who should not get a live nasal spray influenza vaccine or who should speak with their health care provider prior to vaccination include:¹²
  • Children younger than two years old
  • Adults 50 years and older
  • Persons with a history of a severe allergic reaction to any component of the vaccine or to a previous dose of any influenza vaccine
  • Children two through 17 years of age who are receiving aspirin or undergoing aspirin-containing therapy
  • Pregnant women
  • History of Guillain-Barre Syndrome (GBS) within six weeks of a previous dose of influenza vaccine
  • People with weakened immune systems (immunosuppression)
  • Children two to four years of age who have asthma or have had a history of wheezing in the past 12 months
  • People who have taken influenza antiviral drugs within the previous three weeks
  • Persons 5 and older with asthma
  • People who care for severely immunocompromised persons who require a protective environment
  • Individuals with a cerebrospinal fluid leak
  • Individuals with medical conditions which may put them at higher risk of serious flu complications (i.e., kidney, heart, or lung disease, kidney or liver disorders, metabolic or neuromuscular or neurologic disorders)
  • People without a spleen, or those without a functioning spleen
  • Individuals with cochlear implants
  • People who are moderately or severely ill.

Is Flu Vaccine Recommended for Children? 

One consideration with the recommended widespread administration of annual flu shots to all children over six months of age is interference with the acquisition of influenza antibodies acquired after recovery from type A or B influenza infections. The question of whether it is better for healthy children, who rarely suffer complications from flu, to get the flu and develop permanent immunity to that flu strain or whether it is better for children to get vaccinated every year to try to suppress all flu infection in early childhood is a question that has yet to be adequately answered by medical science.

Although in the past the flu vaccine has not been recommended for healthy children, today vaccination of children between the ages of six months and 18 years is strongly recommended by the Advisory Committee on Immunization Practices (ACIP) of the CDC¹³ and New Jersey, Ohio, Connecticut, New York City, and Rhode Island require influenza vaccine for daycare and/ or preschool entry.¹⁴

On August 19, 2020, Massachusetts public health officials announced that all children six months of age and older attending child care, pre-school, kindergarten, K-12 and colleges and universities in Massachusetts will be required to get the influenza vaccine “to reduce flu-related illness and ​the overall impact of respiratory illness during the COVID-19 pandemic.” Massachusetts was the first state to require influenza vaccinations for all students attending kindergarten, primary and secondary schools and colleges and universities.¹⁵

Is influenza vaccine safe during pregnancy?

In years past, pregnancy was also a contraindication to flu vaccine but, today, the CDC recommends flu vaccine for all pregnant women.¹⁶

Initially, most influenza vaccines were classified as Category B or C drugs, which meant that adequate and well-controlled studies on pregnant women had not been conducted and it was not known whether these vaccines could cause fetal harm when administered to a pregnant woman or if they could affect reproduction capacity.¹⁷ 

In 2015, the FDA removed pregnancy categories due to concerns of confusion and oversimplification and replaced it with the Pregnancy and Lactation Labeling Rule.¹⁸ This rule affects all influenza vaccine products submitted for approval after June 30, 2015. As new language is phased in, information on risks associated with vaccinating while pregnant will appear in 8.1 of each vaccine’s product insert under Risk Summary. NVIC encourages consumers read this information carefully prior to receiving a vaccine.

Prior to the FDA licensing of all influenza vaccines, drug companies did not test the safety and effectiveness in pregnant women¹⁹ and little data is available on biological responses to these vaccines that could affect pregnancy and birth outcomes.²⁰

Pregnant women should also be aware that the multi-dose flu vaccine contains thimerosal, which is a mercury derivative. Mercury is toxic to the brain and has been found to be associated with brain damage and developmental delays in babies whose mothers were exposed to high levels of mercury during pregnancy.^{21 22}

In December 2016, Congress signed the 21^st Century Cures Act into law. This new law protects vaccine manufacturers from lawsuits in civil court if an FDA licensed vaccine given to a pregnant woman causes the injury or death of her unborn child in the womb.^{23 24} As a result, policies relating to compensating vaccine injuries sustained by an unborn child in the womb are being developed.

In 2017, a CDC funded study reported that women vaccinated in the early part of their pregnancy with a flu vaccine containing the pandemic H1N1 (H1N1pdm09) strain and who also had been previously vaccinated the prior season with a H1N1pdm09-containing flu vaccine had a greater risk of miscarriage in the first four weeks following vaccination. The CDC conducted further research among women who were pregnant during the 2012-2013 through 2014-2015 flu seasons and eligible to receive the flu vaccine. This study, which contradicted their previous findings, reported that the influenza vaccine did not cause miscarriages in the women evaluated in the study.^{25 26}

What about mercury in the influenza vaccine?

In 1999, the Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA)²⁷ directed the vaccine manufacturers to take mercury out of all childhood vaccines.

In October 2001, the Institute of Medicine issued a report that said it is "biologically plausible" that mercury-containing vaccines could cause injury to the brain but there have been “too few scientific studies conducted to prove conclusively that mercury in vaccines has caused brain damage.”²⁸

Nevertheless, the Institute of Medicine recommended that drug companies take all mercury out of all vaccines and over-the-counter drugs.

In compliance with this recommendation a preservative-free flu vaccine formulated for children ages six to 35 months, with only a trace amount of thimerosal, is available. All multi-dose vials of influenza vaccine contain thimerosal.²⁹

Many influenza vaccines in the U.S. also contain the mercury preservative, Thimerosal, in amounts above federal safety guidelines. Thimerosal free influenza vaccine is also licensed in the U.S. and it is advisable to request these vaccines in advance from your healthcare provider, if your preference is the Thimerosal free version. Click here to determine which vaccines are thimerosal free.

IMPORTANT NOTE: NVIC encourages you to become fully informed about Influenza and the Influenza 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.

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