The fact that you haven't seen anything proven is not a meaningful statement. The data's there of you look.
The most successful countries at fighting the pandemic are also champions at wearing masks.
There's plenty of studies from the flu and SARS times showing that certain masks reduce the risk of an individual infection and any mask worn by an infected individual will reduce risk of transmission.
What we don't have is a peer reviewed study that masks stop a pandemic, because such a study is incredibly hard to set up and we didn't have enough pandemics yet.
No. Masks don't explain the dramatic differences in the IFR. That's the Infection Fatality Rate. Masks only explain the R differences.
Most countries are around 0.2% IFR, which you call successful, some are at around 1%. Masks just prevent infections (by about 5%), but does not influence the percentage to die when you got infected. The biggest factors (called comorbidities) for the differences are the age curve (significant drop at around >75), pre-existing conditions like diabetes, obesity, ... the effectiveness of the healthcare system, air pollution, but it could also be just two different kinds of strains. The 0.2% strain, and the 1% strain, because there's a clear geographical line between the two.
At the beginning it was the 45° parallel north latitude, at the end it was the Germany/France border, 10° east longitude.
The R differences on the other hand are clearly influenced by the measures: social distancing, travel restrictions, hygiene, lockdown, masks,...
No... what? Because you seem to be agreeing with me that masks prevent infections. No infections, no pandemic.
But I wonder where you got the 5% from, because Hong Kong, South Korea and others are doing spectacular at preventing infections compared to e.g. the US or Europe, much better than 5%.
The most successful countries at fighting the pandemic are also champions at wearing masks.
There's plenty of studies from the flu and SARS times showing that certain masks reduce the risk of an individual infection and any mask worn by an infected individual will reduce risk of transmission.
What we don't have is a peer reviewed study that masks stop a pandemic, because such a study is incredibly hard to set up and we didn't have enough pandemics yet.