Some independent experts say the paper is a welcome update, given the pervasive idea that wearing a mask is a mostly altruistic act.
“It’s been a real deficiency in the messaging about masking to say that it only protects the other,” said Charles Haas, an environmental engineer and expert in risk assessment at Drexel University. “From the get go, that never made sense scientifically.”
In other settings, too, from hospitals to hair salons, face coverings may have driven down rates of overall infection, perhaps preventing disastrous outbreaks. And countries like Japan, Taiwan and South Korea, where outbreaks quickly sparked a wave of widespread masking, managed to rein in the number of coronavirus-related hospitalizations and deaths early on.
Even in the United States, the slow upward tick in mask-wearing has coincided with what appears to be a more modest death rate, compared to the surge that occurred after the virus first made landfall in North America. These trends have also likely been influenced by increased testing, a downward shift in the average age of people contracting the virus and improvements in coronavirus treatments. Still, masks probably aren’t hurting things, Dr. Gandhi said.
The Coronavirus Outbreak ›
Frequently Asked Questions
Updated July 27, 2020
Should I refinance my mortgage?
- It could be a good idea, because mortgage rates have never been lower. Refinancing requests have pushed mortgage applications to some of the highest levels since 2008, so be prepared to get in line. But defaults are also up, so if you’re thinking about buying a home, be aware that some lenders have tightened their standards.
What is school going to look like in September?
- It is unlikely that many schools will return to a normal schedule this fall, requiring the grind of online learning, makeshift child care and stunted workdays to continue. California’s two largest public school districts — Los Angeles and San Diego — said on July 13, that instruction will be remote-only in the fall, citing concerns that surging coronavirus infections in their areas pose too dire a risk for students and teachers. Together, the two districts enroll some 825,000 students. They are the largest in the country so far to abandon plans for even a partial physical return to classrooms when they reopen in August. For other districts, the solution won’t be an all-or-nothing approach. Many systems, including the nation’s largest, New York City, are devising hybrid plans that involve spending some days in classrooms and other days online. There’s no national policy on this yet, so check with your municipal school system regularly to see what is happening in your community.
Is the coronavirus airborne?
- The coronavirus can stay aloft for hours in tiny droplets in stagnant air, infecting people as they inhale, mounting scientific evidence suggests. This risk is highest in crowded indoor spaces with poor ventilation, and may help explain super-spreading events reported in meatpacking plants, churches and restaurants. It’s unclear how often the virus is spread via these tiny droplets, or aerosols, compared with larger droplets that are expelled when a sick person coughs or sneezes, or transmitted through contact with contaminated surfaces, said Linsey Marr, an aerosol expert at Virginia Tech. Aerosols are released even when a person without symptoms exhales, talks or sings, according to Dr. Marr and more than 200 other experts, who have outlined the evidence in an open letter to the World Health Organization.
What are the symptoms of coronavirus?
Does asymptomatic transmission of Covid-19 happen?
- So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.
The idea that face coverings can curb disease severity, although not yet proven, “makes complete sense,” said Linsey Marr, an expert in virus transmission at Virginia Tech. “It’s another good argument for wearing masks.”
Dr. Marr and other researchers are still sussing out exactly how much inbound or outbound virus different types of masks block. But based on a wealth of past evidence and recent observations, the amount that’s filtered out is probably high — perhaps 50 percent or more of the larger aerosols being sent in both directions, Dr. Marr said. Certain coverings, like N95 respirators, will do better than others, but even looser-fitting cloths can waylay some viral particles.
Still, some experts are not ready to embrace all ideas about two-way protection.
What’s outlined in Dr. Gandhi’s paper “is still just a theory, and needs more research,” said Nancy Leung, an epidemiologist at the University of Hong Kong. While there’s good evidence that masks reduce the spread of viruses within a population, it’s much harder to nail down how face coverings influence symptoms, Dr. Leung said, in part “because of the difficulty in conducting those studies.”