Sorry if I'm being pedantic, but what you've written is not strictly true.
Four starting premise:
1.
Covid19 spreads 'person to person' OR 'person touching contaminated surface with hand and then placing near mouth, nose or eyes'.
2. People touch their face 200+ times a day.
3. Masks are effective at capturing droplets, which is a main transmission route of coronavirus, and some studies have estimated a roughly fivefold protection versus no barrier alone .
https://www.theguardian.com/world/2...ect-me-from-coronavirus-covid-19-myths-busted
4.
The evidence says mask reduce likelihood of covid19 airborne particles from entering your mouth or nose, but not 100% guarantee .
Scenario: Let's say I'm infected but asymptomatic, so not in strict quarantine but following social distancing. When out of home, wearing mask stops me from spreading covid19 particles onto my hand, which I could then spread onto surfaces, which others would later touch eg: (eg a shopping basket, trolly or a door handle). Next person who touches surface also not wearing mask, then touches mouth/nose and could get infected.
In that instance, wearing a mask helps me not to spread covid19, and not wearing mask has acted as a 'spreading' agent, and would contribute to infecting others.
Scenario: Let's say I'm uninfected. I wear a mask outside. Unknowingly I touch a surface in a shop where covid19 was alive (eg a shopping basket, trolly or a door handle). Because I'm wearing a mask, it reminds me not to touch face with hand until I get out of shop or get home. After I leave shop or when I get home, I wash hands with soap or use 60%+ alcohol based hand sanitiser. Then take off mask and can touch my face without risk.
In that instance, the mask has acted as a 'protection' barrier, and most likely saved me from being infected.
