Cambridge hospital’s mask upgrade appears to eliminate Covid-19 risk to staff
An NHS hospital that upgraded the type of face masks used by staff on Covid-19 wards recorded a dramatic fall of up to 100% in hospital-acquired coronavirus infections among those workers, research has indicated.
Addenbrooke’s hospital in Cambridge upgraded the masks from fluid resistant surgical masks (FRSMs) to filtering face piece 3 (FFP3) respirators, with the change made in late December in response to its own staff testing data.
Public Health England (PHE) had, until recently, recommended that healthcare workers caring for Covid-19 patients should use FRSMs as respiratory protective equipment.
PHE recommended that an FFP3 respirator should be used if an aerosol-generating procedure were being carried out, such as inserting a breathing tube into a patient’s windpipe.
Guidance has been updated recently to oblige NHS organisations to assess the Covid-19 risk to staff and provide FFP3 respirators where appropriate.
Addenbrooke’s has been testing staff for Covid-19 since the start of the pandemic, even when workers showed no symptoms.
Tests indicated that healthcare workers caring for Covid-19 patients were at greater risk of infection than staff on non-Covid wards, even when using the recommended respiratory protective equipment. In response, the hospital’s infection control committee upgraded the type of masks used by staff on Covid-19 wards.
Prior to the upgrade, Covid-19 cases were higher among staff on Covid-19 wards compared with non-Covid wards in seven out of the eight weeks analysed by researchers.
Following the change in protective equipment, the incidence of infection on the two types of ward was similar.
The research has not yet been peer-reviewed, but is being released early because of the urgent need to share information relating to the pandemic.
Dr Chris Illingworth, from the MRC Biostatistics Unit at Cambridge University, said: “Before the face masks were upgraded, the majority of infections among healthcare workers on the Covid-19 wards were likely due to direct exposure to patients with Covid-19.
“Once FFP3 respirators were introduced, the number of cases attributed to exposure on Covid-19 wards dropped dramatically – in fact, our model suggests that FFP3 respirators may have cut ward-based infection to zero.”
According to the researchers’ mathematical model, the risk of direct infection from working on a non-Covid-19 ward was low throughout the study period, and consistently lower than the risk of community-based exposure.
By contrast, the risk of direct infection from working on a Covid-19 ward before the change in respiratory protective equipment was considerably higher than the risk of community-based exposure: staff on Covid-19 wards were at 47 times greater risk of acquiring infection while on the ward than staff working on a non-Covid-19 ward.
Dr Michael Weekes, from Cambridge University’s Department of Medicine, said: “Our data suggests there’s an urgent need to look at the PPE offered to healthcare workers on the frontline.
“Upgrading the equipment so that FFP3 masks are offered to all healthcare workers caring for patients with Covid-19 could reduce the number of infections, keep more hospital staff safe and remove some of the burden on already stretched healthcare services caused by absence of key staff due to illness.
“Vaccination is clearly also an absolute priority for anyone who hasn’t yet taken up their offer.”