Pfizer Covid-19 vaccine efficacy against severe disease due to COVID-19 was 96.7% and preserved up to (not only) six months.

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Published in the New England Journal of Medicine. Peer-reviewed. Pfizer’s vaccine. 45,000+ participants. 6 countries. 152 sites. Sound methodology. Real-world data. Vaccine efficacy against severe disease due to COVID-19 was 96.7% and preserved UP TO (NOT only) six months.

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The New England Journal of Medicine

Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant

List of authors.

  • Jamie Lopez Bernal, F.F.P.H., Ph.D.,
  • Nick Andrews, Ph.D.,
  • Charlotte Gower, D.Phil.,
  • Eileen Gallagher, Ph.D.,
  • Ruth Simmons, Ph.D.,
  • Simon Thelwall, Ph.D.,
  • Julia Stowe, Ph.D.,
  • Elise Tessier, M.Sc.,
  • Natalie Groves, M.Sc.,
  • Gavin Dabrera, M.B., B.S., F.F.P.H.,
  • Richard Myers, Ph.D.,
  • Colin N.J. Campbell, M.P.H., F.F.P.H.,
  • Gayatri Amirthalingam, M.F.P.H.,
  • Matt Edmunds, M.Sc.,
  • Maria Zambon, Ph.D., F.R.C.Path.,
  • Kevin E. Brown, M.R.C.P., F.R.C.Path.,
  • Susan Hopkins, F.R.C.P., F.F.P.H.,
  • Meera Chand, M.R.C.P., F.R.C.Path.,
  • and Mary Ramsay, M.B., B.S., F.F.P.H.
  • et. al.

August 12, 2021
N Engl J Med 2021; 385:585-594
DOI: 10.1056/NEJMoa2108891
Chinese Translation 中文翻译

Abstract

Background

The B.1.617.2 (delta) variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (Covid-19), has contributed to a surge in cases in India and has now been detected across the globe, including a notable increase in cases in the United Kingdom. The effectiveness of the BNT162b2 and ChAdOx1 nCoV-19 vaccines against this variant has been unclear.

Methods

We used a test-negative case–control design to estimate the effectiveness of vaccination against symptomatic disease caused by the delta variant or the predominant strain (B.1.1.7, or alpha variant) over the period that the delta variant began circulating. Variants were identified with the use of sequencing and on the basis of the spike (S) gene status. Data on all symptomatic sequenced cases of Covid-19 in England were used to estimate the proportion of cases with either variant according to the patients’ vaccination status.

Results

Effectiveness after one dose of vaccine (BNT162b2 or ChAdOx1 nCoV-19) was notably lower among persons with the delta variant (30.7%; 95% confidence interval [CI], 25.2 to 35.7) than among those with the alpha variant (48.7%; 95% CI, 45.5 to 51.7); the results were similar for both vaccines. With the BNT162b2 vaccine, the effectiveness of two doses was 93.7% (95% CI, 91.6 to 95.3) among persons with the alpha variant and 88.0% (95% CI, 85.3 to 90.1) among those with the delta variant. With the ChAdOx1 nCoV-19 vaccine, the effectiveness of two doses was 74.5% (95% CI, 68.4 to 79.4) among persons with the alpha variant and 67.0% (95% CI, 61.3 to 71.8) among those with the delta variant.

Conclusions

Only modest differences in vaccine effectiveness were noted with the delta variant as compared with the alpha variant after the receipt of two vaccine doses. Absolute differences in vaccine effectiveness were more marked after the receipt of the first dose. This finding would support efforts to maximize vaccine uptake with two doses among vulnerable populations. (Funded by Public Health England.)


Read the whole article here:
https://www.nejm.org/doi/full/10.1056/NEJMoa2108891

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