New data suggest that Pfizer and Modana vaccines may be less effective against Delta


NS New preprint research Expressing concerns about the effectiveness of the mRNA vaccine against Delta, especially Pfizer, has already attracted the attention of top executives of the Biden administration.

What they are saying: The study found that the Pfizer vaccine was only 42% effective against July infections, which were predominantly delta mutants. “If it’s not a call to wake up, I don’t know what it is,” a senior Biden official told Axios.

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News promotion: This study, conducted by nference and the Mayo Clinic, compared the efficacy of the Pfizer and Modana vaccines in the Mayo Clinic health system over a period from January to July.

  • Overall, the Moderna vaccine was found to be 86% effective against infections during the study period, and the Pfizer vaccine was found to be 76%. The Moderna vaccine was 92% effective against hospitalization, and the Pfizer vaccine was 85%.

  • However, when the prevalence of delta mutants in Minnesota exceeded 70%, the effectiveness of the vaccine against infection dropped sharply in July.

  • Moderna was 76% effective against infection and Pfizer was only 42% effective.

  • Similar results were obtained in this study in other states. In Florida, for example, those who were fully vaccinated with Moderna had a July infection risk of about 60% lower than those who were fully vaccinated with Pfizer.

Important reason: Although not yet peer-reviewed, this study raises serious questions about the long-term efficacy of both vaccines, especially Pfizer’s efficacy.

  • It is unclear whether the results mean a decrease in effectiveness over time, a decrease in effectiveness against the delta, or a combination of both.

  • “Based on previous data, this is a combination of both factors. The Moderna vaccine is very likely to be more effective than the Pfizer vaccine. Delta is the predominant strain and the Pfizer vaccine is effective. Sexual persistence seems to be low. “

  • His team added that they are working on a follow-up attempt to distinguish between the durability of the two vaccines and their efficacy against Delta.

Yes, but: No data have previously found that vaccine protection against severe illness and death is significantly less against Delta, and studies have made significant differences in the complications resulting from breakthrough infections based on which vaccine. Someone got it that points out that it doesn’t seem to be.

  • And experts warned against rushing to a conclusion.

  • “This is a kind of amazing discovery that needs to be confirmed before accepting its effectiveness,” said John Moore, a virologist at Cornell University.

Line spacing: Both shots use mRNA, but there is a big difference between them.

  • For example, Moderna is given at a higher dose than Pfizer, with slightly different time intervals between shots.

  • “There are some differences between those known to be similar vaccines … None of these variables are obvious smoking guns, but the dose is most likely a factor. It seems expensive, “Moore said.

In the statement “We expect to be able to develop and manufacture a bespoke vaccine against the mutant in about 100 days after the decision, subject to regulatory approval,” Pfizer said with BioNTech.

Editor’s Note: This story has been updated to include a statement from Pfizer.

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