evidence: Absolutely nothing changed about the efficacy of masks between February and April 2020. The CDC may have developed concerns about asymptomatic infection, but the agency didn't uncover new data showing that universal masking would blunt viral transmission any better than it had in years past. Indeed, such evidence was "scarce," as a March 2020 Lancet Respiratory Medicine article pointed out. [...] Moreover, randomized clinical trials have shown inconsistent or inconclusive results, with some studies reporting only a marginal benefit or no effect of mask use. Thus, surgical and similar masks are often considered to be ineffective. On the other hand, observational data show that regions or facilities with a higher percentage of the population wearing masks have better control of COVID-19.