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#294 Real World Evidence for COVID-19 Vaccines


CLINICAL QUESTION
QUESTION CLINIQUE
What is the real-world effectiveness for currently available COVID-19 vaccines?


BOTTOM LINE
RÉSULTAT FINAL
Similar to clinical trials, real world cohort and case-control studies find COVID-19 infections are reduced by >90% with two doses of mRNA vaccines. Single doses of either mRNA or AstraZeneca vaccine decreases infections by ~60% and hospitalizations by 70-80%. Vaccine effectiveness appears similar for variants of concern and are safe for pregnant women.



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EVIDENCE
DONNÉES PROBANTES
  • From relatively short cohort/case-control studies or registries. Fully vaccinated defined as 7- or 14-days post-second dose.
  • Israel national vaccination (Pfizer) program of 6.5 million adults ≥16 years old.1 New COVID-19 cases in the program’s initial 10 weeks was compared to vaccine status. Full vaccination decreased risk of:
    • All COVID-19 infections: By 97%.
    • Hospitalizations and deaths: By 98% and 99% respectively.
    • Limitations: The same individuals contributed time to unvaccinated, partially vaccinated and fully vaccinated calculations.
  • United Kingdom case-control study, persons ≥70 years with COVID-19 (n=44,590) linked to vaccine status.2 Single dose of either Pfizer or AstraZeneca reduced:
    • Symptomatic infections: ~60% (~1 month after either vaccine).
    • Hospitalizations: 80% (either vaccine).
    • Death: ~85% [Pfizer (AstraZeneca death rates not reported)].
  • Ontario four-month case-control study, adults ≥16 years:3
    • Single-dose (Pfizer or Moderna) reduced:
      • Symptomatic infection: 60%.
      • Hospitalization or death: 70%.
    • Two-doses reduced:
      • Symptomatic infection: 91%.
      • Hospitalization or death: 98%.
Context
  • Findings similar to clinical trials.4
  • Variants of Concern (VOC):
    • Two doses of Pfizer or AstraZeneca reduces symptomatic delta variant infections or hospitalizations similar to non-VOC infections.5
    • Pfizer or Moderna vaccination reduces symptomatic infection or hospitalizations in four current VOC (alpha, beta/gamma, delta) similar to non-VOC.6
      • Two doses are better than one.6
  • Safety in Pregnancy:
    • 35,691 pregnant women received Pfizer or Moderna vaccine (29% 1st trimester, 43% second trimester, 26% third trimester):7
      • Adverse pregnancy outcomes with vaccine same as baseline risk.7
    • Babies born to pregnant women with COVID-19 are twice as likely to develop severe perinatal morbidity and mortality.8
    • Pregnant women with COVID-19 have 50% greater risk of maternal morbidity or mortality.8
  • Pregnant women should be offered COVID-19 vaccine.9
  • Recommendations for vaccinated individuals available: Canada or United States.10,11


Steve Cooper July 22, 2021

Good info

Mona Reck July 30, 2021

Good

Martin Withers January 1, 2022

Good review

Ronald Maier January 10, 2022

confirms knowledge


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Author(s)
Auteur(s)
  • Michael R Kolber BSc MD CCFP MSc
  • Paul Fritsch MD CCFP
  • Jennifer Young MD CCFP
  • Nicolas Dugré PharmD MSc BCPAC
  • Alexander Singer MB BAO BCh CCFP
  • Tony Nickonchuk BScPharm

1. Haas EJ, Angulo FJ, McLaughlin JM, et al. Lancet. 2021; Published Online May 5, 2021. https://doi.org/10.1016/ S0140-6736(21)00947-8

2. Bernal JL, Andrews N, Gower C, et al. BMJ. 2021;373: n1088. http://dx.doi.org/10.1136/bmj.n1088

3. Chung H, Nasreen S, Sundaram ME, et al. MedRxiv preprint May 24, 2021; doi: https://doi.org/10.1101/2021.05.24.21257744;

4. Kolber MR, Fritsch P, Price M, et al. Can Fam Physician. 2021; 67:185-6.

5. Stowe J, Andrews N, Gower C, et al. Effectiveness of COVID-19 vaccines against hospital admission with the Delta (B.1.617.2) variant. Available at: https://bit.ly/3xBEiXy Accessed June 29, 2021

6. Nasreen S, He S, Chung H, et al. MedRxiv preprint doi: https://doi.org/10.1101/2021.06.28.21259420; July 3, 2021.

7. Shimabukuro TT, Kim SY, Myers TR, et al. N Engl J Med. 2021; 384:2273-82.

8. Villar J, Ariff S, Gunier RB, et al. JAMA Pediatr. doi:10.1001/jamapediatrics.2021.1050

9. Poliquin V, Castillo E, Boucoiran I, et al. Society of Obstetrics and Gynecology. Statement of COVID-19 Vaccination in Pregnancy. Available at: https://bit.ly/3ebTUK3 Accessed June 8, 2021

10. Centre for Disease Control (CDC): Choosing Safer Activities. Available at: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/pdfs/choosingSaferAct.pdf?v=1. Accessed June 1, 2021

11. Public Health Agency of Canada (PHAC). Vaccinated Against COVID-19: What does it mean to me? Available at: https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/awareness-resources/vaccinated-against-covid-19-public-health-measures.html. Accessed June 27, 2021.

Authors do not have any conflicts of interest to declare.

Les auteurs n’ont aucun conflit d’intérêts à déclarer.