Early U.S. monitoring finds allergic reactions after first Pfizer COVID-19 vaccine doses

In late December 2020, U.S. health officials began monitoring for safety issues as the first doses of the Pfizer-BioNTech COVID-19 vaccine were given. This early report looked for cases of severe allergic reactions, known as anaphylaxis, in people who received their first shot between December 14 and 23. The report confirmed that some cases of anaphylaxis were reported during this period. The report did not provide specific numbers on how many reactions occurred or how that number compared to the total number of vaccinations given. This was a preliminary surveillance report, not a detailed research study. Its main purpose was to quickly flag potential safety signals for further investigation. Because it was an early look at data from the first days of the rollout, it cannot tell us how frequent these reactions are in the wider population. Readers should know that severe allergic reactions to vaccines are rare but can be serious. This report helped vaccination sites prepare by ensuring they had supplies and staff ready to manage such reactions. Anyone with a history of severe allergies to vaccine ingredients should discuss vaccination with their doctor.