Adverse Event Prevention - Vaccine Safety

The risk of vaccine adverse events can be reduced by screening for precautions and contraindications prior to administration of any vaccine. The Advisory Committee on Immunization Practices (ACIP) provides General Best Practice Guidelines for Immunization, which address contraindication and precautions. They also provide information on some common conditions that may be misunderstood as contraindications, and in which vaccination is generally safe. 


Contraindications are situations where a vaccine should generally not be given. This usually means a person has a condition that increases the risk for a serious adverse reaction after vaccination. Because many contraindications are temporary, vaccinations often can be administered later when the condition leading to a contraindication no longer exists. Certain conditions are commonly misperceived as contraindications (i.e., they are not medically valid reasons to not be vaccinated). 

CDC provides information about who should not receive certain vaccines, or should wait to receive them.


A precaution is a condition that may increase the chance or severity of a serious adverse reaction, or that may compromise the ability of the vaccine to produce a good immune response. Precautions may be temporary or permanent conditions. In general, vaccines are postponed when a precaution is present. However, situations may arise when the benefit of protection from the vaccine outweighs the risk of an adverse event, and a doctor or healthcare provider may decide to give the vaccine.

According to the ACIP, the presence of a moderate or severe acute illness with or without a fever is a precaution to administration of all vaccines. This is because it may be hard to tell if someone is having an adverse event because they are already ill. However, vaccines can often be given safely during a mild illness, and even while someone is in the hospital. Healthcare providers know how to evaluate a person’s health status and recommend the most appropriate time to vaccinate.  

Specific contraindications to each vaccine can be found in VIS forms, manufacturer product inserts, and ACIP recommendations.