According to an Institute of Medicine report, which statement about vaccine adverse reactions is accurate?

• A. Administering multiple vaccines may trigger the development of type 1 diabetes.
• B. The MMR may be linked to febrile seizures in immunocompromised children.
• C. There is some risk of CNS disorders associated with the hepatitis B vaccine.
• D. Vaccines containing thimerosal are linked to pervasive developmental disorders.

Answer: (B)

The main idea is how the Institute of Medicine evaluates reports of vaccine adverse reactions. They look at the available evidence to see whether a real, causal link exists or if observed associations are possible but not proven, often describing them as small or uncertain risks.

In this case, the statement about the MMR vaccine reflects the idea that vaccines can sometimes cause fever, and fever can trigger febrile seizures in a small subset of children after vaccination. That acknowledges a potential association without claiming a proven cause-and-effect, which is why it’s described as “may be linked.” The risk is considered small and the benefit of vaccination remains substantial.

The other claims aren’t supported by credible evidence in the IOM report: there isn’t convincing evidence that administering multiple vaccines triggers type 1 diabetes; there isn’t credible evidence linking hepatitis B vaccine to CNS disorders; and there isn’t credible evidence linking vaccines containing thimerosal to pervasive developmental disorders.