A movie that explains in an easy-to-understand manner why masks are 'more effective than you can imagine' in combating viral infections
Many studies have shown that if certain people wear masks, '
Why Masks Work BETTER Than You'd Think --YouTube
Suppose you have a 'mask that cuts the risk of transmitting a virus to others in half'. In this case, this mask can be described as '50% effective'.
However, if everyone walking around the city wears a '50% effective mask', the effect will be higher than '50%'. Why?
To help you understand this intuitively, consider an extreme example. If there is no one in the world to wear a mask, the benefits of the mask are zero.
If everyone wears a '50% effective mask', infections will be reduced by 50% ...
Instead, it is reduced by 75%.
This is because the mask has both 'protecting the wearer from infection' and 'preventing infection from the wearer'.
Furthermore, 'everyone wears a mask' means 'there are two masks between people'.
Then, the virus spread by one person is first cut by 50% with the mask worn by that person, and then cut by another 50% with the mask of another person.
This is the reason why 'a mask with 50% effect' is 75% effective.
Unfortunately, not everyone wears a mask in reality. Therefore, there are four patterns of contact between infected and non-infected individuals.
The first is the case where both the infected and the contact are not wearing masks. In this case, the benefits of the mask are zero.
The second is the case where only infected people wear masks. In this case, the effect of the mask is 50%.
The third is the case where only the contact person wears the mask. Again, the infection is reduced by 50% as above.
The fourth is the case where both wear masks. As mentioned above, the mask effect is 75%.
Earlier, I found that 'if everyone wears a mask that is 50% effective, the mask effect is 75%.' But what if 50% of people wear masks?
In this case, one-quarter of all contacts are 'without mask', one-quarter is 'only infected person is wearing mask', and one-quarter is 'only contact person is wearing mask'. So, 1/4 is 'both are wearing masks'.
As a result, even if one-half of the people wearing masks are wearing masks, three-quarters of all contacts are wearing masks, and some of them are both wearing masks.
According to intuition, 'If half of the people wear masks that are 50% effective,' 50% x 50% = 25% 'and the infection control rate is 25%.' Indeed, this is correct if the mask has only a one-way effect.
However, as mentioned above, the mask has a bidirectional effect, so the actual suppression effect is 44%. In other words, even if only 50% of people wear a mask that is 50% effective, it is effective in halving the infection.
Regardless of the mask wearing rate or the effect of the mask, the 'actual effect' always exceeds the 'intuition'.
So what if we actually apply this to COVID-19?
So far, it is said that one COVID-19 patient can infect 2.5 people with COVID-19. Epidemiologically speaking, the
If this is reduced by 60% to less than 1, the spread of the infection will be quickly suppressed.
There are several combinations of 'wearing rate' and 'mask effect' that can achieve a 60% reduction, but for example, '60% of people' can achieve it by wearing a '60% effective mask'. I will.
It's important to note that COVID-19 actually expands in a very complex way, as we've eliminated many elements in this movie for clarity.
On top of that, Minute Physics said, 'Even if the effect is not 100% mask, and even if not everyone wears a mask, if enough people wear a mask, they can repel the pandemic.' I concluded.
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