Summary

This health notice discusses the side effects of the three COVID-19 vaccines authorized for use in the United States: the two mRNA vaccines (Pfizer/BioNTech and Moderna), and the adenovirus vaccine (Janssen/Ad26.COV2.S). The majority of side effects are mild to moderate and self-limited, but the Janssen COVID-19 vaccine has recently been associated with a serious clinical syndrome called thrombotic thrombocytopenic syndrome (TTS). This health alert notice provides information for health care providers on common side effects and their management, as well as an in-depth discussion about TTS: counseling patients about risks, recognizing symptoms, and evaluation and management considerations.