Evidence on optimal use of PPE and physical distancing to stop COVID-19

Evidence on optimal use of PPE and physical distancing to stop COVID-19

A new, comprehensive review has provided evidence for the first time on the optimal use of Personal Protective Equipment (PPE) and physical distancing to stop the spread of COVID-19.

Part funded by the World Health Organization and carried out by researchers from universities across the globe, the review examined the optimal use of PPE and physical distancing to help control the spread of the novel coronavirus.

Published in The Lancet, the review showed that using face masks and eye protection, as well as keeping one metre apart from others could be the optimal way to reduce the spread. However, it notes that none of these interventions give complete protection from the infection and that some of the findings around personal protective equipment are supported by low-certainty evidence, with no completed randomised trials.

Stopping the pandemic and informing disease models

The researchers say that the study, which was conducted to inform WHO guidance documents, has immediate and important implications for stopping the pandemic and informing future disease models, as well as for standardising the definition of who has been ‘potentially exposed’ for contact tracing.

So far, the best evidence suggests that COVID-19 is most commonly spread by respiratory droplets, however, the role of aerosol spreading is contested. Different countries have also given different advice on the best safety measures, and the benefits of using facemasks have been debated.

Professor Holger Schünemann from McMaster University in Canada, who co-led the research, said: “Our findings are the first to synthesise all direct information on COVID-19, SARS, and MERS, and provide the currently best available evidence on the optimum use of these common and simple interventions to help ‘flatten the curve’ and inform pandemic response efforts in the community.

“Governments and the public health community can use our results to give clear advice for community settings and healthcare workers on these protective measures to reduce infection risk.”

Analysis from the study showed that for every extra metre away from each other people stand, the risk of infection or transmission may halve. However, the authors note that the certainty of their evidence on physical distancing is moderate and that none of the studies quantitatively evaluated whether distances of more than two metres were more effective, although meta-analyses provided estimates of risk.

How beneficial is PPE?

The studies focussing on eye protection found that face shields, goggles, and glasses were associated with a lower risk of infection, compared with no eye covering, but the authors note that the certainty of the evidence for eye coverings is low. The studies examining the use of facemasks found the risk of infection was also lower (3% compared to 17% when not wearing a mask) but was based on evidence of ‘low certainty’.

For healthcare workers, N95 and respirator masks might be associated with greater protection from viral transmission than surgical masks or similar, and for the general public, face masks are also associated with protection, even in non-health-care settings, with either disposable surgical masks or reusable 12-16 layer cotton ones. The authors emphasise, however, that there are concerns that the use of face masks by the public risks diverting supplies from healthcare workers and other caregivers at the highest risk of infection.

To date, there has been a global shortage of PPE and the authors stress that policymakers will need to address this to ensure they are equally available for all.

Co-author Dr Derek Chu, Assistant Professor at McMaster University, said: “With respirators such as N95s, surgical masks, and eye protection in short supply, and desperately needed by healthcare workers on the front lines of treating COVID-19 patients, increasing and repurposing of manufacturing capacity is urgently needed to overcome global shortages.

“We also believe that solutions should be found for making face masks available to the general public. However, people must be clear that wearing a mask is not an alternative to physical distancing, eye protection or basic measures such as hand hygiene, but might add an extra layer of protection.”

Despite this being the first study to bring together all information regarding PPE and physical distancing for COVID-19, limitations remain, including that few studies assessed the effect of interventions in non-healthcare settings, and that the majority of the evidence came from studies of SARS and MERS. It was also emphasised that the effect of duration of exposure on risk for transmission was not specifically examined.


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