FA16 Immunization Module’s Updates

Adverse Reactions to Vaccines

An adverse reaction to a vaccine is characterized by any unwanted effect that does not help in the production of an immune response leading to immunity. These unwanted effects are often called “side effects” [1].  The frequency and severity of an adverse reaction varies with each vaccine.  The route of administration (intradermal, subcutaneous or intramuscular injection, drops given orally, or intranasal administration) can have an effect on the risks of an adverse reaction.  For this reason, manufacturers make specific recommendations for the route and location that should be used for administration of a vaccine [2].

The type and severity of an adverse reaction often depend on the type of vaccine administered (live attenuated or inactivated). The CDC gives two examples to illustrate this point:

Because the MMR vaccine is a live attenuated vaccine, an adverse reaction could be systemic. Most adverse reactions have symptoms similar to a weakened form of the disease for which the vaccine was created.  Similarly, the most common adverse reaction to the MMR is a mild rash and fever.

However the DTaP vaccine is inactivated vaccine, making it unable to replicate like a normal virus. Symptoms of an adverse reaction are localized to the site of injection and are generally characterized by mild inflammation [1].

In rare cases, an adverse reaction can be caused by an allergic reaction to the vaccine or components of the vaccine used for transport.  Allergic reactions can range in severity from a mild reaction to anaphylaxis.  Researchers have also noted instances of other more serious conditions in the years following a vaccine. These instances are rare, and it is questionable whether a link of causation exists.

Below is a link for the CDC website detailing symptoms and frequency of adverse reactions for specific vaccines (very specific/helpful):

https://www.cdc.gov/vaccines/vac-gen/side-effects.htm#polio

Resources:

[1]: http://www2a.cdc.gov/nip/isd/ycts/mod1/courses/genrec/10905.asp?student_id=

[2]: http://vaccine-safety-training.org/adverse-events-causes.html

  • Josh Baalman