Biden Admin Concerned as Mayo Clinic Study Shows Pfizer Vaccine Dropped to 42% Effective

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  • 03/02/2023


An earlier version of this report failed to loop in some important context related to this study. A second source, Politifact, issued the following information, which we feel is critical when discussing the information released by the Mayo Clinic on COVID-19 and the Pfizer vaccine.

  • The study, which has not yet been peer-reviewed, looked at people who had received at least one dose of the two-shot vaccines. It said the Pfizer vaccine’s effectiveness in preventing COVID-19 infection dropped to 42% in July.
  • Overall, the study said that both the Pfizer and Moderna vaccines are highly effective in preventing hospitalization.
  • As the virus’ delta variant has taken hold this summer, the vast majority of COVID-19 hospitalizations and deaths have occurred among people who were not vaccinated.

A new preprint study raises concerns about vaccine efficacy against the Delta variant, and it seems like the Biden administration is getting worried. 

The study, conducted by the Mayo Clinic, found that the Pfizer vaccine was only 42 percent effective against infection in July. 

“If that’s not a wake up call, I don’t know what is,” a senior Biden official told Axios

Overall, the study found that the Moderna vaccine was 86 percent effective against infection and Pfizer’s was 76 percent; Pfizer’s was 85 percent effective against hospitalization, while Moderna’s was 92 percent. 

However, the vaccines’ effectiveness against infection dropped sharply in July to 76 percent with Moderna and 42 percent with Pfizer. 

This was the case in states like Minnesota and Florida. 

“Based on the data that we have so far, it is a combination of both [a reduction in effectiveness over time and a reduced effectiveness against Delta],” said Venky Soundararajan, a lead author in the study. “The Moderna vaccine is likely - very likely - more effective than the Pfizer vaccine in areas where Delta is the dominant strain, and the Pfizer vaccine appears to have a lower durability of effectiveness.” 

In a statement, Pfizer said it “expect[s] to be able to develop and produce a tailor-made vaccine against that variant in approximately 100 days after a decision to do so, subject to regulatory approval.” 

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