The COVID-19 vaccine rollout averted infection in 10% of NHS patient-facing healthcare staff during the second wave of the pandemic, new research shows today.
Two studies, published in the latest edition of The BMJ, provide essential insights into SARS-CoV-2 infection in health and social care workers that can be used to guide further infection prevention and control measures.
The first study – based on SARS-CoV-2 Immunity and Reinfection Evaluation (SIREN) – by a team from the UK Health Security Agency, University of Oxford, and Imperial College London, said the vaccine rollout from December 2020 prioritised frontline healthcare workers, without which an extra 10% of all patient-facing hospital workers would have been infected, which could have resulted in a 69% higher staff absence rate.
Researchers examined the rate of risk factors for, and the impact of, COVID-19 vaccines during England’s second wave – 1 September 2020-30 April 2021 – in susceptible hospital healthcare workers.
They analysed data from 18,284 clinical, support, and administrative staff who had no evidence of previous infection and who were recruited from 105 NHS hospital trusts in England as part of the SARS-CoV-2 Immunity and Reinfection Evaluation (SIREN) study.
Participants completed a survey about their demographic, household and occupational characteristics when they enrolled and went on to complete fortnightly questionnaires that included if they had been vaccinated.
The study participants also had fortnightly PCR tests and monthly antibody tests throughout the study period.
There were 2,353 (13%) infections among participants during the second wave, peaking in late December 2020 and decreasing from January 2021, in line with rapid vaccination coverage among healthcare workers and a national lockdown.
Being under 25 years old, living in a household of five or more people, having frequent exposure to patients with COVID-19, working in an emergency department or inpatient ward setting, and being a healthcare assistant were all factors that increased the likelihood of infection in the second wave.
They also found that each additional day without being vaccinated multiplied a participant’s odds of infection by 2%.
Although this is an observational study and cannot establish cause, the authors say SIREN is a large study that is well positioned to explore the incidence of SARS-CoV-2 infection in the hospital workforce.
The study “reinforces the importance of vaccination among healthcare workers during a significant wave of the SARS-CoV-2 pandemic in England”, they say, adding: “Greater understanding of transmission dynamics among healthcare workers, particularly according to role and setting, will support NHS trusts in protecting their workforce and patients from SARS-CoV-2 infection and potentially other seasonal winter viruses.”
In the OpenSAFELY study, researchers from the University of Oxford, London School of Hygiene and Tropical Medicine, and the MRC Integrative Epidemiology Unit, compared the effectiveness of the Pfizer-BioNTech and the Oxford-AstraZeneca COVID-19 vaccines against infection in 317,341 health and social care workers in England vaccinated between 4 January and 28 February 2021.
They used data from the OpenSAFELY research platform and found there was strong protection from both vaccines and no substantial differences between the two vaccines in rates of infection or COVID-19 related hospital attendance and admission.
Pople D, Monk EJM, Evans S et al. Burden of SARS-CoV-2 infection in healthcare workers during second wave in England and impact of vaccines: prospective multicentre cohort study (SIREN) and mathematical model. BMJ 21 July 2022; doi: 10.1136/bmj-2022-070379
Hulme WJ, Williamson EJ, Green ACA et al. Comparative effectiveness of ChAdOx1 versus BNT162b2 COVID-19 vaccines in health and social care workers in England: cohort study using OpenSAFELY/. BMJ 21 July 2022; doi: 10.1136/bmj-2021-068946
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