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US officials knew covid vaccine safety system was flawed—but turned aside the FDA doctor who alerted them
US officials embraced an algorithm for detecting signals of harm from mRNA covid-19 vaccines that they knew was broken and suppressed efforts to fix it. David Willman reports
Before covid-19 vaccines were rolled out to Americans in December 2020, the US Centers for Disease Control and Prevention (CDC) assured healthcare providers that the agency was on the lookout for any harmful reactions. A key part of the CDC’s strategy was its Vaccine Adverse Event Reporting System (VAERS), which receives such reports after vaccination.
“It is the nation’s frontline system for monitoring vaccine safety and the early warning system for detecting possible vaccine safety problems,” said Tom Shimabukuro, deputy director of CDC’s Immunization Safety Office, on 30 October 2020.
Millions of people were to be vaccinated each week, and the CDC would rely on statistical “data mining” of the VAERS database to quickly identify any safety signals in need of further probing.
Two well recognised, separate algorithms were to be used. The first involved calculating “proportional reporting ratios” (PRRs), which sought to identify types of reactions reported to VAERS disproportionately or more frequently than background rates. The second data mining technique, called “empirical bayesian,” was to be provided by the Food and Drug Administration (FDA), which operated VAERS jointly with the CDC, and the two agencies planned to share and discuss results.1
But in a little noticed September 2022 letter, CDC director Rochelle Walensky said that the agency did not perform PRR analyses for signals until 2022. This was more than a year into the vaccine rollout and was intended, she wrote, “to corroborate” the FDA’s approach. Instead of using the PRR and empirical bayesian methods jointly during the pandemic, Walensky explained that both the CDC and FDA instead “chose to rely” on empirical bayesian, which she characterised as “a …
