Keep wearing masks and social distancing — it works, new McMaster study says

Masks and social distancing can help control the coronavirus but hand washing and other measures are still needed, a new study from Hamilton's McMaster University says.

Researchers concluded single-layer cloth masks are less effective than surgical masks, while tight-fitting N95 masks provide the best protection. A distance of 1 metre (more than 3 feet) between people lowers the danger of catching the virus, while 2 metres (about 6 1/2 feet) is even better.

Eye protection such as eyeglasses or goggles can help too. None of the strategies work perfectly and more rigorous studies are needed, according to the analysis published Monday. The report says "The risk for infection is highly dependent on distance to the individual infected and the type of face mask and eye protection worn."

With the coronavirus still new, health officials have relied on studies involving its cousins, severe acute respiratory syndrome and Middle East respiratory syndrome. The findings come from a systematic review of 44 studies, including seven involving the virus causing COVID-19. The remaining focused on SARS or MERS.

Researchers say their study "identified 172 observational studies across 16 countries and six continents, with no randomised controlled trials and 44 relevant comparative studies in health-care and non-health-care settings." That included 25,697 patients.

"This puts all that information clearly in one place for policymakers to use," said study co-author Dr. Derek Chu of McMaster University in Hamilton. Read the full study here.

The report says "Our findings are, to the best of our knowledge, the first to rapidly synthesise all direct information on COVID-19 and, therefore, provide the best available evidence to inform optimum use of three common and simple interventions to help reduce the rate of infection and inform non-pharmaceutical interventions, including pandemic mitigation in non-health-care settings." 

Still to come are results from more rigorous experiments in Canada and Denmark that are testing masks in randomly assigned groups of nurses and the general public. Until then, the new study in the journal Lancet provides reassurance that masks do help.

Public health officials have given conflicting advice about masks.

The World Health Organization, which funded the new analysis, has said healthy people need to wear a mask only if they are caring for a person with COVID-19. The U.S. Centers for Disease Control and Prevention wants everyone to wear at least a cloth mask when grocery shopping or in similar situations where keeping distance is difficult.