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Covid-19: Pfizer vaccine efficacy was 52% after first dose and 95% after second dose, paper shows

BMJ 2020; 371 doi: https://doi.org/10.1136/bmj.m4826 (Published 11 December 2020) Cite this as: BMJ 2020;371:m4826

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  1. Elisabeth Mahase
  1. The BMJ

The Pfizer and BioNTech covid-19 vaccine may provide some early protection, starting 12 days after the first dose, the peer reviewed results of a phase III trial have found.

The study, published in the New England Journal of Medicine,1 found that vaccine efficacy between the first and second doses was 52% (95% credible interval 29.5% to 68.4%), with 39 cases of covid-19 in the vaccine group and 82 cases in the placebo group.

Seven or more days after the second dose, vaccine efficacy then rose to 95% (90.3% to 97.6%), with eight covid-19 cases reported in the vaccine group and 162 cases in the placebo group.

The vaccine has so far been approved in Canada …

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