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Comment by belorn | Hacker News Reader

Its interesting that the article do not mention a rather interesting finding in the study. For the age groups of < 50 years the effect was not statistically significant with the control and the mask wearing villages having similar rate of covid-19.

Why aren't masks effective to reduce the spread for that age group? The discussion part of the study don't explore it. Is the distancing behavior of people aged 50 or higher different than those below?

I would like to see further studies being done on the younger demographic in order to explain why the data is looking like it is.

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> Why aren't masks effective to reduce the spread for that age group?

This is a good question and I think it is an important one since the title implies a different situation than what was actually tested.

So the 11% reduction was due to an effort to increase mask wearing compliance by means of...

> Providing free masks, informing people about the importance of covering both the mouth and nose, reminding people in-person when they were unmasked in public, and role-modeling by community leaders

It's probably not that masks are less effective on people under 50, but that the information campaign was less effective at influencing that group to wear their masks.

Also, the results are interesting:

> The observers found that just over 13% of people in the villages that received no interventions wore a mask properly, compared with more than 42% of people in the villages where each household received free masks and in-person reminders to wear them.

It seems that there is much more progress that can be made in getting people to wear masks. And we still don't know how effective 95%+ compliance will be at reducing the spread.

Finally, the report does note that villages provided with cloth masks had worse outcomes than those who were provided with surgical masks.

It not established in the study (that I can see in their findings) that people under 50 were wearing mask less than those above 50. The finding only showed that those under 50 did not benefit.

There could be any number of reason why the result of the data look like it is. If those villages are mostly small farming communities it might be that young people spend most of their time outside on the fields or herding animals while the older population spend more time inside. It might be that the older generations after a long hard working life need more active help from younger family members and can't do distancing (like in our elder care facilities). Mask has a rather good track record when people are working inside in close physical proximity to risk groups.

Since the study did not explore those question we can only speculate.

Maybe lower mask adherence among younger people or different behaviors-- older people in villages might stay at home more.

if the latter is true, then wouldn't that be an indicator that masks do not, in fact, work as well as thought?

It could, or it could mean that the protective effect of surgical masks is most pronounced indoors.

They did report that physical distancing increased in villages that were given masks, so that may explain it. Unfortunately they didn't untangle that effect? How do we know to what degree it was the masks vs increased distancing?

I think the limited specificity of their definition of COVID-19 means it is easier to detect effects for populations that have higher incidence.

did you check that the number of counted infections in ages < 50 is enough to get statistical significance per whatever criteria in the study?

Compliance.

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