My sister, a practicing MD, says that cloth masks are worse than nothing because they act as disease reservoirs. N95 masks are single-use. People aren't throwing their homemade masks after every trip outdoors, so any contamination their masks "stopped" is just waiting for the next use to infect the wearer. (She cited a study she'd read, which I can't find, but this Wirecutter article [1] makes a similar argument in the first answer).
That said, that doesn't mean that masks aren't helping in Czechia--they're a potent reminder to everyone to keep their distance, and that their friends and neighbors have bought into the seriousness of the threat. That alone is worth something.
I think the wrong model is the problem. Surgical masks provide small protection to you, but significant protection to others. It isn't for you, it is for everyone else. Think of a mask as portable social distancing.
By catching droplets from (asymptomatic) infected wearers, it reduces the virus on surfaces and in the air. That's the benefit.
> People aren't throwing their homemade masks after every trip outdoors, so any contamination their masks "stopped" is just waiting for the next use to infect the wearer.
The general recommendation is to put them into boiling water after each use for 30 minutes.
Those who have only scarf probably dont do this, but they are still less likely to infect others if they are asymptomatic carriers.
>so any contamination their masks "stopped" is just waiting for the next use to infect the wearer
It's true the virus may linger and infect later, but it might also be destroyed in the meantime. The odds depend on various factors, such as exposure to sunlight, antiviral chemicals, or high temperatures.
That said, that doesn't mean that masks aren't helping in Czechia--they're a potent reminder to everyone to keep their distance, and that their friends and neighbors have bought into the seriousness of the threat. That alone is worth something.
1. https://thewirecutter.com/blog/your-coronavirus-questions-an...