> Cloth masks showed no statistically significant reduction in the spread of Covid-19.

This is a completely false characterization of the article you just linked.

There were significantly fewer COVID-19 cases in villages with surgical masks compared with the control villages. (Although there were also fewer COVID-19 cases in villages with cloth masks as compared to control villages, the difference was not statistically significant.) This aligns with lab tests showing that surgical masks have better filtration than cloth masks. However, cloth masks did reduce the overall likelihood of experiencing symptoms of respiratory illness during the study period.

“Unfortunately, much of the conversation around masking in the United States is not evidence-based,” Luby said. “Our study provides strong evidence that mask wearing can interrupt the transmission of SARS-CoV-2. It also suggests that filtration efficiency is important. This includes the fit of the mask as well as the materials from which it is made. A cloth mask is certainly better than nothing. But now might be a good time to consider upgrading to a surgical mask.”

From the original paper:

--- We find clear evidence that surgical masks lead to a relative reduction in symptomatic seroprevalence of 11.2% (aPR = 0.89 [0.78,1.00]; control prevalence = 0.80%; treatment prevalence = 0.71%). For cloth masks, we find an imprecise zero, although the confidence interval includes the point estimate for surgical masks (aPR = 0.95 [0.79,1.11]; control prevalence 0.67%; treatment prevalence 0.62%). ---

If you go to the chart, you find a 5% relative reduction with a p-value of 0.540 (!)

Regarding reduction in symptoms:

--- Additionally, when we look separately by cloth and surgical masks, we find that the intervention led to a reduction in COVID-like symptoms under either mask type (p = 0.000 for surgical, p = 0.048 for cloth), but the effect size in surgical mask villages was 30-80% larger depending on the specification. In Table A10, we run the same specifications using the smaller sample used in our symptomatic seroprevalence regression (i.e. those who consented to give blood). In this sample we continue to find an effect overall and an effect for surgical masks, but see no effect for cloth masks. ---

There's no intellectually honest way to interpret this data other than "cloth masks have very little effect, if any".

Emphasizing this quote:

However, cloth masks did reduce the overall likelihood of experiencing symptoms of respiratory illness during the study period.

This is really interesting, and I’d like to read the paper - do you have a link?

EDIT: here: https://www.poverty-action.org/publication/impact-community-...

That summary is really hard to draw conclusions from;

“However, cloth masks did reduce the overall likelihood of experiencing symptoms of respiratory illness during the study period.”

And “ A cloth mask is certainly better than nothing. But now might be a good time to consider upgrading to a surgical mask.”

But also “ Although there were also fewer COVID-19 cases in villages with cloth masks as compared to control villages, the difference was not statistically significant.”

I suppose it means there was a difference but it was not statistically significant. Like 5% reduction with 10% certainty.

This is not true. The study found a reduction in COVID-19 symptoms for the cloth mask group. They also found a reduction in seroprevalence for the cloth mask group, but that reduction wasn't statistically significant. "Statistically insignificant" is not the same as "not true". It is very hard to sufficiently power a seroprevalence study.

This is a high-power study with N in the hundreds of thousands.

"Statistically insignificant" is the same as "no reason to believe it is true".