Information Resources

What Do I Need To Know About Vaccines & Infectious Disease?

Updated December 28, 2023

Vaccines and Infectious Disease

NVIC maintains comprehensive information on vaccines and infectious diseases and recommends that individuals visit that portion of our website for more detailed and comprehensive information on this topic. The information below reflects only those questions which are frequently asked.

Q: Now that the diphtheria-pertussis-tetanus vaccine has been switched from DTP (pertussis whole cell form) to DTaP (pertussis acellular form), is the vaccine safe?

A: In 1996, it was recommended that vaccine be switched from use of whole-cell pertussis (DTP) to acellular pertussis (DTaP).

Whole cell DPT vaccine is a relatively crude vaccine that contains B. pertussis bacteria chemically and heat treated. Acellular DTaP contains less endotoxin and less bioactive pertussis toxin. Both DPT and DTaP contain aluminum adjuvants.

Pertussis toxin is an extremely lethal toxin capable of crossing the blood brain barrier and it is used by researchers in laboratories to deliberately induce Experimental Autoimmune Encephalomyelitis (EAE) in lab animals. Pertussis toxin is an ingredient in whole cell DPT vaccine and the acellular DTaP vaccine but it is less bioactive in DTaP.

Whole-cell DPT contains B. pertussis bacteria heat and chemically treated as well as significant amounts of endotoxin (capable of killing animals and humans on its own). There is less endotoxin in DTaP, however both DPT and DTaP contain aluminum adjuvants. Aluminum can kill brain cells and make the blood brain barrier more permeable

Even though the acellular DTaP vaccine is believed to be less reactive than the whole cell DPT vaccine, NVIC still receives reports of serious reactions following DTaP vaccination that are consistent with symptoms and injuries known to be associated with DPT vaccine, including high pitched screaming, fever over 103F, collapse/shock (hypotonic/hyporesponsive episode), convulsions, and encephalopathy.

Infants and children, who have demonstrated one or more of these symptoms following DTAP vaccination (or any other vaccination), should be carefully evaluated by one or more health care professionals before more DTaP or other vaccines are given. If you, as a parent, are concerned that continuing vaccination would harm your child and a doctor is insisting more vaccines be given without your voluntary consent, you should contact another trusted health care professional for a second opinion. If your child has experienced health deterioration after previous vaccinations, it is important listen to your intuition and become totally comfortable before proceeding with more vaccination.

Q: What is the difference between DTP, DTaP and Tdap?

A: DPT vaccine is a combination of three inactivated bacterial vaccines: diphtheria, pertussis and tetanus. There are many different forms and combinations of these vaccines licensed for use in the United States. Some versions of the vaccine are only appropriate for adults and adolescents (Tdap, Td and TT). Various versions of the vaccine for infants and young children include DPT (whole cell pertussis), which is no longer used in the U.S.; DTaP (acellular pertussis) which was licensed in 1996 for babies; and DT (diphtheria, tetanus).

Q: Where can I get split-up, single dose DTaP vaccine for my baby or preschooler or split-up single dose Tdap for my adolescent?

A: The "P" part of the combination DPT or DTaP vaccine is the vaccine which is associated with the most cases of brain inflammation and permanent brain damage. Infants who cannot have the "P" or pertussis (whooping cough) portion of the vaccine are generally given the DT vaccine.

Your child's pediatrician or health department should be able to obtain the DT vaccine if your child has had a previous reaction after receiving DPT or DTaP vaccine. Separate doses of the three vaccines for children are not available any longer in the U.S.. For children, the only combinations are DT, DTaP or Tdap.

Q: Where can I get split-up, single dose MMR vaccine for my baby or preschooler?

A: The MMR shot contains three live virus vaccines (Measles-Mumps-Rubella). Some parents want to administer the three vaccines separately and space them out. However, the separate measles, mumps and rubella vaccines are no longer available in the U.S. because the manufacturer has stopped marketing the separate vaccines. If state laws require only two doses of rubella vaccine but three doses of measles vaccine, the only option is for a child to get three doses of MMR.

Q: Our doctor said my wife had no antibodies to rubella and recommended that she get the MMR after our child was born. About a week after she got the vaccine, she broke out in a rash, had a fever, and all her joints were stiff and painful. Could this be a reaction to the vaccine? My wife is nursing, was my child exposed to this vaccine?

A: The symptoms you have reported have been associated with adverse reactions to the MMR. The MMR (measles-mumps-rubella) vaccine contains three attenuated live virus vaccines and a nursing infant would be exposed to the live viruses in the vaccine through the breast milk. All live virus vaccines can transmit vaccine strain virus through breast milk and other bodily fluids, such as waste products. There have been documented cases of vaccine strain chickenpox transmitted from a recently vaccinated child to other children and to pregnant women. The live oral polio vaccine (OPV) recommended for use in the U.S until 1999 could transmit vaccine strain polio virus and cause paralytic polio in vaccine recipients or those who came into contact with an individual receiving OPV.

Q: Does my newborn need the Hepatitis B vaccine in the hospital?

A: Unless the mother is positive for Hepatitis B or there are other risk factors (such as the need for frequent blood transfusions), hepatitis B is not a disease commonly encountered by infants. Hepatitis B is primarily transmitted by IV drug users and those with multiple sexual partners.

Hepatitis B vaccine is routinely given to infants in the newborn nursery of hospitals at between two hours and 12 hours of age. If you do not want your infant to be injected with hepatitis B vaccine at birth, it is important to make that notation on the written forms that are signed by mothers upon entering the hospital to give birth.

An additional precaution is taken by some mothers by having the baby's father or another family member accompany the newborn at all times during the first 24 hours when the baby is not with the mother. Unfortunately, there are cases where medical personnel disregard the written instructions and administer the hepatitis B vaccine to newborns despite written and verbal instructions by the parents to defer the hepatitis B vaccination until a later date. For more information and resource links, view the related FAQ on Infant Hepatitis B vaccination here.

Q: My neighbor's children were vaccinated for chickenpox (varicella zoster) and one developed chickenpox lesions. Can my child get chickenpox from the vaccine or from children who have been recently vaccinated?

A: Yes, about 4 to 10 percent of children who have been recently vaccinated have developed a rash with chickenpox lesions within 7 to 21 days after vaccination. It is thought that children who develop lesions after getting varicella zoster vaccine are contagious and can transmit varicella zoster vaccine strain chickenpox to others.

A few studies have documented transmission of vaccine-strain chickenpox from a recently vaccinated person to non-vaccinated children who then developed chickenpox lesions. Specifically, a study showed that five months after two siblings were immunized with varicella zoster vaccine, one developed chickenpox. Two weeks later the second sibling got a mild case of chickenpox and the virus was found to be vaccine-type, which gave evidence for transmission of vaccine strain chickenpox from sibling to sibling. Another study described transmission of vaccine strain chickenpox from a recently vaccinated mother to her two children.

Q: My child is immune-compromised and has not had the chickenpox vaccine. Should he be vaccinated? What should I do if he is exposed to chickenpox?

A: This is a question that needs to be discussed with one or more qualified health care providers. Although the CDC recommends that immunocompromised persons get chickenpox vaccine, it is a live virus vaccine and the risks and benefits as well as timing of vaccination need to be carefully considered. NVIC has been informed by some parents that the anti-viral drug Acyclovir has been prescribed by their child's physician to treat chickenpox. Other parents have indicated that their child's physician prescribed hyper-immune gamma globulin.

Q: Is it true that children can get polio from the polio vaccine?

A: Yes, some children who get the oral (by mouth) live polio vaccine (OPV) have developed cases of vaccine-strain paralytic polio. Outbreaks of vaccine-strain polio have been documented in India, Indonesia and Nigeria. In 1999, the U.S. stopped using the live oral polio vaccine (OPV) and switched to the inactivated polio vaccine (IPV), which is injected. NVIC is not aware of any cases of vaccine-strain polio associated with use of the inactivated polio vaccine.

Q: Is it true that monkey viruses contaminated polio vaccines?

A: Yes, SV40 (the 40th simian virus to be identified in polio vaccines) did contaminate both early inactivated Salk vaccine and live oral polio (Sabin) vaccines made using monkey kidney tissues. Original OPV seed stocks were contaminated with SV40. Today, SV40 has been identified in brain, bone and lung tumors affecting children and adults. There is ongoing controversy about the association between SV40 contaminated polio vaccines and increases in brain, bone and lung cancer in children.

Q: I'm interested in getting the smallpox vaccine. Where can I get it and are there any issues that I should be concerned about?

A: Smallpox vaccine is not routinely administered in the U.S. to civilians. You should contact your physician or local health department. After September 11, 2001, there were concerns about a bioterrorism attack using weaponized smallpox virus. Federal officials made tentative plans to extend stored smallpox vaccine supplies and offer smallpox vaccinations to all Americans. NVIC has prepared information to educate the public about smallpox and smallpox vaccine. Federal plans to use old smallpox vaccine supplies were eventually scrapped and new smallpox vaccines are being developed under Bioshield legislation passed since 9/11.

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