Beware of Blaylock. In my opinion he's a dishonest crank.
He argues there are no studies proving masks protect against the flu.
Why flu when we're talking about Covid-19? He says
"no studies have been done to demonstrate that either a cloth mask or the N95 mask has any effect on transmission of the COVID-19 virus. Any recommendations, therefore, have to be based on studies of influenza virus transmission."
But the review of literature that he cites for his core argument also says:
"Eight of nine retrospective observational studies found that mask and/or respirator use was independently associated with a reduced risk of severe acute respiratory syndrome (SARS)."
Covid-19 is caused by a SARS virus.
See that? He fails to tell his readers that multiple studies show masks are effective against SARS viruses and instead focuses on influenza.
Why? Not because he's an honest researcher but because it gives him the answer he wants.
Good stuff! Might I trouble you for a link to that if you have it? Google doesn't find it.