Covid-19 vaccine side effects

History shows many examples of serious adverse events from vaccines brought to market in periods of enormous pressure and expectation.

There were contaminated polio vaccines in 1955, cases of Guillain-Barré syndrome in recipients of flu vaccines in 1976, and narcolepsy linked to one brand of influenza vaccine in 2009.1819

“Finding severe rare adverse events will require the study of tens of thousands of patients, but this requirement will not be met by early adoption of a product that has not completed its full trial evaluation,” Harvard drug policy researchers Jerry Avorn and Aaron Kesselheim recently wrote in JAMA.20

Covid-19 vaccine trials are currently designed to tabulate final efficacy results once 150 to 160 trial participants develop symptomatic covid-19—and most trials have specified at least one interim analysis allowing for the trials to end with even fewer data accrued.

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