A simple Google search of “CDC mask studies” takes the internet surfer to this continuously updated page on the effectiveness of masking. https://www.cdc.gov/coronavirus/2019...sars-cov2.html
The CDC has the most up to date information on the majority of questions that pertain to COVID…all written on an 8th grade level but complete with references to the original studies so that people can weigh the strengths and weaknesses of the evidence for themselves if they don’t trust the CDC. All one needs to do is type “CDC” before the question…