An observational cohort study on the incidence of SARS-CoV-2 infection and B.1.1.7 variant infection in healthcare workers by antibody and vaccination status

  1. Sheila F Lumley
  2. Gillian Rodger
  3. Bede Constantinides
  4. Nicholas Sanderson
  5. Kevin K Chau
  6. Teresa L Street
  7. Denise O’Donnell
  8. Alison Howarth
  9. Stephanie B Hatch
  10. Brian D Marsden
  11. Stuart Cox
  12. Tim James
  13. Fiona Warren
  14. Liam J Peck
  15. Thomas G Ritter
  16. Zoe de Toledo
  17. Laura Warren
  18. David Axten
  19. Richard J Cornall
  20. E Yvonne Jones
  21. David I Stuart
  22. Gavin Screaton
  23. Daniel Ebner
  24. Sarah Hoosdally
  25. Meera Chand
  26. Oxford University Hospitals Staff Testing Group
  27. Derrick W Crook
  28. Anne-Marie O’Donnell
  29. Christopher P Conlon
  30. Koen B Pouwels
  31. A Sarah Walker
  32. Tim EA Peto
  33. Susan Hopkins
  34. Timothy M Walker
  35. Nicole E Stoesser
  36. Philippa C Matthews
  37. Katie Jeffery
  38. David W Eyre
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Abstract

Background

Natural and vaccine-induced immunity will play a key role in controlling the SARS-CoV-2 pandemic. SARS-CoV-2 variants have the potential to evade natural and vaccine-induced immunity.

Methods

In a longitudinal cohort study of healthcare workers (HCWs) in Oxfordshire, UK, we investigated the protection from symptomatic and asymptomatic PCR-confirmed SARS-CoV-2 infection conferred by vaccination (Pfizer-BioNTech BNT162b2, Oxford-AstraZeneca ChAdOx1 nCOV-19) and prior infection (determined using anti-spike antibody status), using Poisson regression adjusted for age, sex, temporal changes in incidence and role. We estimated protection conferred after one versus two vaccinations and from infections with the B.1.1.7 variant identified using whole genome sequencing.

Results

13,109 HCWs participated; 8285 received the Pfizer-BioNTech vaccine (1407 two doses) and 2738 the Oxford-AstraZeneca vaccine (49 two doses). Compared to unvaccinated seronegative HCWs, natural immunity and two vaccination doses provided similar protection against symptomatic infection: no HCW vaccinated twice had symptomatic infection, and incidence was 98% lower in seropositive HCWs (adjusted incidence rate ratio 0.02 [95%CI <0.01-0.18]). Two vaccine doses or seropositivity reduced the incidence of any PCR-positive result with or without symptoms by 90% (0.10 [0.02-0.38]) and 85% (0.15 [0.08-0.26]) respectively. Single-dose vaccination reduced the incidence of symptomatic infection by 67% (0.33 [0.21-0.52]) and any PCR-positive result by 64% (0.36 [0.26-0.50]). There was no evidence of differences in immunity induced by natural infection and vaccination for infections with S-gene target failure and B.1.1.7.

Conclusion

Natural infection resulting in detectable anti-spike antibodies and two vaccine doses both provide robust protection against SARS-CoV-2 infection, including against the B.1.1.7 variant.

Summary

Natural infection resulting in detectable anti-spike antibodies and two vaccine doses both provided ≥ 85% protection against symptomatic and asymptomatic SARS-CoV-2 infection in healthcare workers, including against the B.1.1.7 variant. Single dose vaccination reduced symptomatic infection by 67%.

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