Lessons learned will prove crucial in controlling a second wave of COVID-19

The intervention that proved far more important was universal masking – requiring all hospital staff to wear surgical masks all the time.

“If you look at the health care workers who got sick,” Dr. Warshawsky said, “the majority of them got sick not because they didn’t protect themselves properly when they were in a room with a known COVID patient ....

but because they didn’t protect themselves at all when they were in a room with a patient they didn’t know was a COVID patient or a colleague who they didn’t know had COVID. A lot of the transmission was health care worker to health care worker.”

The lesson of universal masking – that simple face coverings reduce the spread of COVID-19 if worn consistently by everyone – applies outside hospitals, too.

The evidence is not airtight, but it is growing by the day.

An analysis of 172 observational studies, most of them pre-COVID-19, concluded that disposable surgical masks and reusable cotton masks were associated with a degree of protection for the general public, especially if combined with hand washing and physical distancing.

A study of sailors aboard the USS Theodore Roosevelt, a navy ship that suffered an outbreak that infected almost 1,500 and killed one, found that sailors who wore masks were significantly less likely to be infected than those who didn’t.

In Germany, where mask mandates were enacted in different regions at different times in April, a study comparing the regions concluded that “face masks reduce the daily growth rate of reported infections by around 40 [per cent.]”

Now that cute masks are a fashion statement and rudimentary versions are sold in Ziploc bags at variety stores, it seems strange to recall that Canadian public-health officials, including Chief Public Health Officer Theresa Tam, once advised against wearing them.

Her stand changed as the evidence did – and as it dawned on everyone that crafty types could sew reusable masks that offered at least some protection without depleting the inadequate supplies of medical-grade personal protective equipment for health workers.

Now masks are mandatory in indoor public places in several major Canadian cities, which should help blunt the impact of a second wave.

“It’s an extra layer of protection,” said Jennifer Kwan, a Burlington family doctor who helped found the advocacy group Masks4Canada. “Masks should be seen as giving us the freedom to return back to normalcy.”