In their view, this is not about protecting yourself but about protecting others, by minimising the risk of you passing on the infection.

In the US, government experts point to the growing scientific evidence that people can release the virus even if they don’t show any symptoms – what’s known as “asymptomatic transmission”.

That’s why public mask-wearing is now official US policy, as in many other countries.

And to allay concerns about a drain on precious PPE for medical professionals, the CDC advocates making your own face covering – using anything from scarves to T-shirts.

Studies have shown that these “informal” masks can trap a significant proportion of any virus you might breathe out so could be invaluable where social distancing isn’t possible – including supermarket checkouts and public transport.

As the UK’s advisers weigh their advice to government, they’ll be considering the role that face coverings may play as lockdown measures start to be eased – wearing them may help cut the risks of a second spike in cases.

But they’ll also worry that people might assume some kind of mask makes them safe and that they’ll become careless about other crucial measures like handwashing.