Among vaccine recipients during the Pfizer clinical trials, 8.8% reported experiencing any reaction they considered to interfere with daily activity; the most common symptoms were fatigue (4.2%), headache (2.4%), muscle pain (1.8%), chills (1.7%), and injection site pain (1.4%). Of note, more people experienced these side effects after the second dose than after the first dose.
Among vaccine recipients during the Moderna clinical trials, 9.1% reported local injection site reaction and 16.5% reported side effects with the most common being including fever, headache, fatigue, and muscle aches and pains.
Additionally, no specific safety concerns were identified for the Pfizer and Moderna vaccines in subgroup analyses by age, race, ethnicity, underlying medical conditions, or previous SARS-CoV-2 infection.