Joe Biden proclaimed, “Wearing masks is not a political statement, it is a scientific imperative.” He was wrong. There is little evidence supporting generalized use of masks.
A pre-COVID systemic review of interventions to combat the spread of respiratory viral diseases by the highly regarded Cochrane Library found that medical/surgical mask wearing makes little or no difference to the outcome of influenza or influenza-like illnesses compared to not wearing a mask.
A recent review of the literature reported two randomized controlled clinical trials of the effectiveness of masking in COVID-19. One failed to demonstrate a statistically significant benefit. The second found small, marginally statistically significant reductions in viral transmission for surgical masks but not for cloth masks. Thirteen of 14 tests assessing mask-wearing in non-COVID respiratory infections failed to find a statistically significant benefit for masks.
Randomized controlled clinical trials are the gold standard in medical research because randomization minimizes the effect of unmeasured confounding variables and researcher bias that can occur in observational studies.