Reactogenicity

Origin

The term reactogenicity was coined by the US Food and Drug Administration (FDA). All vaccines can induce reactogenicity, but reactogenicity is more likely in vaccines containing an adjuvant, which is a chemical additive intended for enhancing the recipient's immune response to the antigen that is present in a vaccine. Reactogenicity describes the immediate short-term reactions of a system to vaccines and should not be confused with the long-term consequences sequelae. Assessments of reactogenicity are carried out to evaluate the safety and usability of an experimental vaccine (see Investigational New Drug). It is unclear whether a higher degree of reactogenicity to a vaccine correlates with more severe adverse events, which would require hospitalization or are life-threatening. Adverse events have been linked to a higher degree of reactogenicity; however, the links might have been coincidental. After assessing large databases relating to these events for many years, the FDA has not been able to make such a correlation.

Definition

The US National Institutes of Health (NIH) has provided the following definition of reactogenicity:

The following is an example of a functional scale for assessing reactogenicity or other parameters not specifically listed in the toxicity table: 0 = Absence of the indicated symptom 1 = Mild (awareness of a symptom but the symptom is easily tolerated) 2 = Moderate (discomfort enough to cause interference with usual activity) 3 = Severe (incapacitating; unable to perform usual activities; requires absenteeism or bed rest) 4 = Life-threatening}}

References

References

1. (24 September 2019). "The how's and what's of vaccine reactogenicity". npj Vaccines.
2. (25 March 2011). "DMID Interventional Template". NIH.