Three Shots of Pfizer–BioNTech Vaccine Better Than Two

New study assessed the the primary series of two doses of the Pfizer-BioNTech COVID-19 vaccination effectiveness against infection, hospitalization, and death up to 8 months after vaccination, and also assessed the effectiveness of 3 doses of the vaccine up to 3 months after vaccination.

Electronic health records of 3.1 million members of Kaiser Permanente in Southern California from December 14, 2020, to December 5, 2021 were evaluated.

During the study period, 197,535 (6.3%) patients were infected with SARS-CoV-2, and of those, 15,786 (8%) were admitted to the hospital. During the study period, the predominant variant was delta, and not omicron.

  • Two-dose vaccine effectiveness against infection declined from 85% during the first month after vaccination to 49% up to 8 months following vaccination.
  • Two-dose vaccine effectiveness against hospitalization remained high (90%) throughout the 8 months and did not wane, except among people who were 75 years of age and older, or who had compromised immune systems.
  • For people who were immunocompromised, the protection against hospitalization dropped to 74%, and for those 75 and older, it was 77%.
  • Three-dose vaccine effectiveness was 88% against infection and 97% against hospitalization within the first 3 months after vaccination.

“What we see from this research is that the public health impact of a third dose to prevent severe disease is substantial,” Tartof said.

“Importantly, all studies that have evaluated the vaccine effectiveness of a third dose — including ours — have shown a meaningful improvement in vaccine effectiveness against a broad range of SARS-CoV-2 outcomes.”

Source: Medindia

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