The findings are reported by a team at the University of Cambridge and Cambridge University Hospitals (CUH) NHS Foundation Trust. The research has not yet been peer-reviewed, but is being released early because of the urgent need to share information relating to the pandemic.
Until recently, advice from Public Health England recommended that healthcare workers caring for patients with COVID-19 should use fluid resistant surgical masks type IIR (FRSMs) as respiratory protective equipment; if aerosol-generating procedures were being carried out (for example inserting a breathing tube into the patient’s windpipe), then the guidance recommended the use of an FFP3 respirator. PHE has recently updated its guidance to oblige NHS organisations to assess the risk that COVID-19 poses to staff and provide FFP3 respirators where appropriate.
Since the start of the pandemic, CUH has been screening its healthcare workers regularly for SARS-CoV-2, even where they show no symptoms. They found that healthcare workers caring for patients with COVID-19 were at a greater risk of infection than staff on non-COVID-19 wards, even when using the recommended respiratory protective equipment. As a result, its infection control committee implemented a change in respiratory protective equipment for staff on COVID-19 wards, from FRSMs to FFP3 respirators.
Prior to the change in respiratory protective equipment, cases were higher on COVID-19 wards compared with non-COVID-19 wards in seven out of the eight weeks analysed by the team. Following the change in protective equipment, the incidence of infection on the two types of ward was similar.
The results suggest that almost all cases among healthcare workers on non-COVID-19 wards were caused by community-acquired infection, whereas cases among healthcare workers on COVID-19 wards were caused by both community-acquired infection and direct, ward-based infection from patients with COVID-19 – but that these direct infections were effectively mitigated by the use of FFP3 respirators.
To calculate the risk of infection for healthcare workers working on COVID-19 and non-COVID-19 wards, the researchers developed a simple mathematical model.
Image: Healthcare worker wearing FFP3 mask
Credit: Cambridge University Hospitals NHS Foundation Trust
Reproduced courtesy of the University of Cambridge