COVID-19 Vaccine Coverage and Effectiveness among Healthcare Workers in England

Pavankumar Kamat


May 07, 2021


  • In a cohort of healthcare workers in England, vaccine coverage was very high 2 months after the roll-out of approved COVID-19 vaccines in the UK.

  • The BNT162b2 mRNA (Pfizer-BioNTech) vaccine reduced the incidence of asymptomatic and symptomatic infections in vaccinated vs unvaccinated healthcare workers.

Why this matters

  • The findings emphasise the importance of vaccinating working-age adults to reduce SARS-CoV-2 infections. 

Study details

  • Interim analysis of the prospective SIREN study involving 23,324 healthcare workers and support staff (median age, 46.1 years) across 104 sites of publicly funded National Health Service hospitals in England.

  • Funding: UK Department of Health and Social Care; Public Health England; National Institute for Health Research.

Key results

  • By 5 February 2021, 89% of participants had received at least 1 dose of a COVID-19 vaccine (BNT162b2, 94%; ChAdOx1, 6%) and 8% had received 2 doses (BNT162b2, 99.9%; ChAdOx1, 0.1%).

  • During follow-up of 2 months, the incidence of COVID-19 decreased in the vaccinated vs unvaccinated cohort:

  • unvaccinated: 14 infections/10,000 person-days;

  • vaccinated, 21 days post-first dose: 8 infections/10,000 person-days; and

  • vaccinated, 7 days post-second dose: 4 infections/10,000 person-days.

  • The vaccine effectiveness of BNT162b2 against infection (symptomatic and asymptomatic) was

    • 70% (95% CI, 55-85%) 21 days after the first dose; and

    • 85% (95% CI, 74-96%) 7 days after the second dose.


  • Short follow-up period.

  • Population may not be representative of all healthcare workers in the UK.


Hall VJ, Foulkes S, Saei A, Andrews N, Oguti B, Charlett A, Wellington E, Stowe J, Gillson N, Atti A, Islam J, Karagiannis I, Munro K, Khawam J, Chand MA, Brown CS, Ramsay M, Lopez-Bernal J, Hopkins S; SIREN Study Group. COVID-19 vaccine coverage in health-care workers in England and effectiveness of BNT162b2 mRNA vaccine against infection (SIREN): a prospective, multicentre, cohort study. Lancet. 2021 Apr 23 [Epub ahead of print]. doi: 10.1016/S0140-6736(21)00790-X. PMID: 33901423  View full text

This clinical summary originally appeared on Univadis, part of the Medscape Professional Network.


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