The Czech government is encouraging countries around the world to slow the spread of the coronavirus through mask-wearing by the general public.

The Central European country’s #Masks4All campaign began online with a viral video by science populariser Petr Ludwig, arguing that masks — whether N95, surgical-grade, or homemade from simple fabric — can play a key role in reducing infection, by blocking the droplets from coughing, breathing, and so on which carry the coronavirus.

The video was shared by the mayor of the Czech capital of Prague, and within a remarkably short period of time the government heeded Ludwig’s call and made masks compulsory throughout the country, which soon achieved near-100 per cent mask use — thanks in large part to a national effort by ordinary Czechs to sew masks at home, leaving the more sophisticated versions for health professionals working in a clinical setting.

Ludwig has now taken his campaign worldwide, with an English-language video making the case for masks endorsed by the Czech government’s minister of health Adan Vojtech, who makes an appearance at the end of the video — complete with his own mask — to ask other governments to follow Czechia’s lead.

“I recommend to all fellow ministers and governments to implement population-wide use of facemasks, even homemade ones,” Vojtech says.

“Today we see that this was one of the most important decisions we have made, and if it can help here, it can help anywhere.”

German medical association @BAEKaktuell calls on people to wear makeshift #masks at all times. Needed NOW: A public info campaign to get this going in #Germany

What about @jensspahn doing his next presser with a fancy mask? #masks4all #covid19 https://t.co/VMrjeTIild pic.twitter.com/8TCRXOCH1D — Boris Ruge (@RugeBoris) March 27, 2020

There has been some dispute over the usefulness of masks, with the World Health Organization (WHO) claiming they should only be worn by doctors, nurses, and people confirmed to be infected.

However, mask proponents argue that people can begin shedding the virus before they show any symptoms — if they ever show any symptoms — which makes the WHO guidance the medical equivalent of closing the stable door after the horse has bolted.

Mask proponents concede that the coronavirus itself is too small to be blocked by a homemade or even a surgical-grade mask, but argue that it does not have to block the virus, just the droplets which carry it — and cite studies which show that masks do indeed reduce viral shedding more than threefold.

As protection for those who are not yet infected, masks seem to have a less dramatic — though still significant — impact, but some virologists argue that even if they cannot prevent infection entirely, they can play a key role in reducing the initial “viral load” when a person becomes infected.

A smaller viral load at the time of infection means the virus has to multiply many more times before it can reach dangerous levels, and the body has more time to ramp up its immune system before it can be overwhelmed — a form of “flattening the curve” at the level of the individual.

Masks proponents also point out that they can serve as an important reminder for people not to touch their mouth or nose unconsciously at times when their hands may be infected.

Follow Jack Montgomery on Twitter: @JackBMontgomery