A health worker administered a third dose of the Pfizer-BioNTech Covid-19 vaccine at a nursing home in Worcester, Pennsylvania, United States, on Wednesday, August 25, 2021.
Hannah Beier | Bloomberg | Getty Images
The side effects of Covid booster shots are similar to those felt after the second dose and are more likely to affect younger people, Pfizer said in new data transmitted to the Food and Drug Administration while searching for approval to distribute booster shots in the United States
Pfizer’s Phase 3 study of booster doses, which included a group of about 300 participants aged 18 to 55 years, found that 63.7% experienced fatigue after getting their boosters, 48.4% had headaches, and 39.1% felt muscle pain. The majority of reactions to the reinforcement were moderate or moderate in severity, the company said in a 52-page report released by the agency Wednesday. The company, along with BioNTech, is seeking emergency FDA approval to administer third-party doses to people 16 years of age or older in the United States.
Pfizer previously evaluated the side effects on the second dose recipients of 2,682 aged 16 to 55 years and found that 61.5% developed fatigue, 54% suffered headaches and 39.3% treated muscle pain.
The study also tracked adverse events among 306 booster recipients, of whom 44 developed at least one unexpected side effect. The most common adverse event, swelling of the lymph nodes, occurred in 16 of the participants.