The Ambiguous Science on Masks

Masks have become one of the more prevalent and enduring symbols of the pandemic. In the United States, many state and local governments have, at one time or another, required masking, and there have been calls for a broad federal mask mandate. Workplaces have required masks for their employees, customers, and vendors. And those who refuse to wear masks have been subject to criticism and shaming.

All this assumes that masking reduces the risk of COVID infection. Numerous political leaders, health care authorities, and major media sources have claimed that “face masks work”—whether they are high-grade “N95” respirators, disposable surgical masks, or the simple multi-ply cloth masks that most of us (myself included) have been wearing in public for going-on two years now.

Take, for instance, this oft-linked New York Times animation on how masks obstruct water droplets containing the SARS-CoV-2 virus that causes COVID. It depicts a few dozen computer-generated circles entering and getting enmeshed in a web of mask fibers. Yet, though the animation is titled, “Masks Work. Really. We’ll Show You How,” it presents no data showing that masks really work at blocking enough airborne virus to reduce COVID rates.

The question of how effective masks are at preventing airborne infection has long been the subject of scientific research. Consider a couple of recent summaries of studies in the Cochrane Systematic Reviews, the highly reputable series of medical lit reviews. One review, examining several studies of the transmission of influenza-like illnesses, found: