LONDON, June 10 — Population-wide facemask use could push Covid-19 transmission down to controllable levels for national epidemics and could prevent further waves of the pandemic disease when combined with lockdowns, according to a UK study published Wednesday.

The research, led by scientists at the Britain’s Cambridge and Greenwich Universities, suggests lockdowns alone will not stop the resurgence of the new SARS-CoV-2 coronavirus, but that even homemade masks can dramatically reduce transmission rates if enough people wear them in public.

"Our analyses support the immediate and universal adoption of facemasks by the public,” said Richard Stutt, who co-led the study at Cambridge.

He said the findings showed that if widespread mask use were combined with social distancing and some lockdown measures, this could be "an acceptable way of managing the pandemic and re-opening economic activity” long before the development and public availability of an effective vaccine against Covid-19, the respiratory illness caused by the coronavirus.

The study’s findings were published in the Proceedings of the Royal Society A scientific journal.

The World Health Organization updated its guidance on Friday to recommend that governments ask everyone to wear fabric face masks in public areas where there is a risk to reduce the spread of the disease.

In this study, researchers linked the dynamics of spread between people with population-level models to assess the effect on the disease’s reproduction rate, or R value, of different scenarios of mask adoption combined with periods of lockdown.

The R value measures the average number of people that one infected person will pass the disease on to. An R value above 1 can lead to exponential growth.

The study found that if people wear masks whenever they are in public it is twice as effective at reducing the R value than if masks are only worn after symptoms appear.

In all scenarios the study looked at, routine facemask use by 50 per cent or more of the population reduced Covid-19 spread to an R of less than 1.0, flattening future disease waves and allowing for less stringent lockdowns.

"We have little to lose from the widespread adoption of facemasks, but the gains could be significant,” said Renata Retkute, who co-led the study. — Reuters