COMMENT:

Q: Is there any point in wearing a cloth mask when I go outside to prevent myself getting Covid?

A: The medical establishment is quick to correctly point out that cloth masks are essentially useless for blocking Covid-19 or other viruses, because their fibres have gaps much too big to prevent passage of breathed-in particles.

And that's certainly true, if all we are concerned about is whether a cloth mask filters out tiny inhaled particles. But what if we're not talking about blocking inhaled viruses, but blocking something much larger, like our own hands?

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The main way respiratory viruses including Covid-19 get into our bodies is through our noses and mouths. Doctors call this droplet spread, but it's easier to think of it as "Touch Your Face and Give Yourself Covid" spread.

We know that people, on average, touch their faces five to 25 times an hour. [More on this in an upcoming column.]

We also know that coughing Covid-19 patients spread invisible droplets all around them. If we could see the process it would look like someone blowing spoonfuls of flour around a room for hours on end. By the end of a day, the room's surfaces would be coated.

A grandparent, roommate, or nurse could then come along, touch things, and go about their day, carrying enough virus with them on their hands — and touching their face enough times in a day — to infect their own mucous membranes.

Bullseye for Covid-19!

Remember, Covid-19 cannot penetrate surfaces — it needs us to deliver it on to the right surface: the lining of our lips, mouth, nose, or eyes.

If there are enough virions, or viral particles, that person will become the next patient.

In our battle with Covid-19, masks serve as physical reminders for us not to touch our own faces, even if they have little ability to block inhaled viral particles.

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Do we know for certain if cloth masks help reduce respiratory illness? No, because people's health behaviours are fiendishly hard to study accurately, and what research there has been, with other non-Covid infections, has been of limited quality.

Some of the better studies suggest that if actually worn correctly, masks significantly reduce one's chance of a respiratory infection. This applies to healthcare workers as well as community members alike. The big challenge, though, even in the studies, is getting people to wear them at all.

There's one thing about which the research is definite: if you are coughing, wearing a mask vastly decreases the amount of infectious droplets you disperse. For that reason alone masks make sense.

As long as you apply, remove, and launder masks correctly, and perform very frequent hand hygiene, cloth masks seem a cheap and reasonable option to help healthy people avoid touching their faces, and sick patients avoid spreading their infection.

Dr Gary Payinda is an emergency doctor working in Northland. He writes for the Herald from the frontline