Economists and perhaps others will benefit from seeing the results of this large-scale randomized controlled trial on wearing masks, in Bangledesh, which studied N=342,126 adults with three study arms: cluster randomized Villages and households with no intervention, with free cloth masks, and with free surgical masks. Participants also received information and local  reminders.

Here is the Yale research paper by economist Jason Abaluck et al describing the experiment.

The Impact of Community Masking on COVID-19: A Cluster Randomized Trial in Bangladesh. https://elischolar.library.yale.edu/cowles-discussion-paper-series/2642/

August, 2021

Here is a popular summary in the Atlantic from September 4, 2021

https://www.theatlantic.com/ideas/archive/2021/09/masks-were-working-all-along/619989/

The study shows the superiority of surgical masks over cloth masks, and the both sets of masks achieved a roughly ten percent reduction in symptomatic seroprevalence. This is less than perfect, but the study interventions were only able to increase the wearing of masks from 13% to 42% and raise social distancing from 24% to 29%. Recall that the study was done in Bangladesh.