Severe reactions from specific immunizations

In rare cases, some people have severe reactions to immunizations. Some of these reactions are related to the measles, mumps, and rubella (MMR) vaccine and to the pertussis vaccine (DPT) that was given in the past.

A child who has a severe reaction after being given an immunization should most likely not receive additional doses of that vaccine.

Reactions from the measles, mumps, and rubella (MMR) vaccine may include:

• Inflammation of the tissues around the brain (encephalitis). This occurs in only about 1 of every 1 million doses of the measles vaccine.
• A temporary drop in the number of platelets, which help in blood clotting. In rare cases, this leads to bleeding problems.

Some people believe that the thimerosal or other components of the measles-mumps-rubella (MMR) vaccine can cause autism. The MMR vaccine has never contained thimerosal. Also, research shows no association between the MMR vaccine and autism.¹ Autism that appears to occur following MMR vaccine is most likely coincidental timing. Children are immunized at about 1 year of age, which is typically about the same time the first signs of autism are noticed.

Reactions from the whooping cough (pertussis) vaccine in the DPT shot included:

• Seizures within 3 days after the shot (injection).
• Persistent, severe screaming or crying for over 3 hours or high-pitched crying within 48 hours after the shot.
• Collapsing episodes within 48 hours after the shot.
• Unexplained fever of 104.5F or higher within 48 hours after the shot.

Some people who received the older DPT shot may have had some of these severe reactions. But they do not tend to occur with today's vaccines for whooping cough. The shots used today are DTaP and Tdap.

Other reactions

Severe reactions to the tetanus (Td) vaccine are very unusual. In rare cases, older adults who have repeated doses may have redness and pain at the place where the shot was given.

Polio vaccines (IPV) given by injection do not cause severe reactions. The oral polio vaccine is no longer used in the United States.

Pneumococcal conjugate vaccine (PCV) may cause pain at the site of the shot as well as fever.

Citations

1. Demicheli V, et al. (2007). Vaccines for measles, mumps and rubella in children. Cochrane Database of Systematic Reviews (1). Oxford: Update Software.