Sweden has seen the vast majority of those fatally infected come from nursing homes. "Once we know how the virus got into our elderly care facilities, the government can make recommendations and take measures to try to stop that, because that is the biggest tragedy of all this, that it has gotten into the nursing homes," Olofsdotter told NPR.

Spate of new research supports wearing masks to control coronavirus spread

Four months of discord about the coronavirus pandemic have transformed the cloth mask into a potent political symbol, touted by Democrats as a key part of communal responsibility, labeled by some GOP leaders as a sign of government overreach and as a scarlet letter pinned on the weak.

But as partisan interests sew symbolism and controversy into masks, scientists are trying to provide answers about how effectively those masks prevent transmission of the novel coronavirus, and what role they should play in efforts to limit its spread.

Several new studies published this month support wearing masks to curb the transmission of the virus. The broadest, a review funded by the World Health Organization and published in the journal Lancet, concluded that data from 172 observational studies indicate wearing face masks reduces the risk of coronavirus infection.