Reactogenicity Prediction after Administration of COVID 19 Vaccines - mRNA Based

In December 2020, 2 mRNA-based COVID-19 vaccines (Pfizer-BioNTech and Moderna) were granted Emergency Use Authorization by the US Food and Drug Administration as 2-dose series and recommended for use by the Advisory Committee on Immunization Practices. In late February 2021, the US Food and Drug Administration granted Emergency Use Authorization for a third COVID-19 vaccine, a single-dose adenovirus vector-based vaccine from Janssen (Johnson & Johnson).In clinical trials of the mRNA-based 2-dose vaccines, participants reported local and systemic reactions (reactogenicity). Frequently reported reactions included injection site pain, fatigue, and headache; greater reactogenicity was reported following the second dose. Continued monitoring of reactogenicity of COVID-19 vaccines outside of clinical trial settings may provide additional information for health care practitioners and the public about transient local and systemic reactions following COVID-19 vaccination.