Adverse Events More Likely With Some COVID-19 Vaccine Batches: Data

Senator presses US health agencies for answers.

The Pfizer-BioNTech COVID-19 vaccine is prepared for administration at a vaccination clinic on Sept. 22, 2021. Frederic J. Brown/AFP via Getty Images

Some lots of COVID-19 vaccines caused significantly more adverse events than others, according to newly published information.

Some batches were linked to as many as 1,650 serious problems, while some produced zero reported issues, according to the data, which was obtained by the Informed Consent Action Network and presented on the website OpenVAERS.