FAQ's on the Coronavirus Outbreak

Updated July 16, 2020

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?

Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.

What’s the best material for a mask?

Scientists around the country have tried to identify everyday materials that do a good job of filtering microscopic particles. In recent tests, HEPA furnace filters scored high, as did vacuum cleaner bags, fabric similar to flannel pajamas and those of 600-count pillowcases. Other materials tested included layered coffee filters and scarves and bandannas. These scored lower, but still captured a small percentage of particles.

Is it harder to exercise while wearing a mask?

A commentary published this month on the website of the British Journal of Sports Medicine points out that covering your face during exercise “comes with issues of potential breathing restriction and discomfort” and requires “balancing benefits versus possible adverse events.” Masks do alter exercise, says Cedric X. Bryant, the president and chief science officer of the American Council on Exercise, a nonprofit organization that funds exercise research and certifies fitness professionals. “In my personal experience,” he says, “heart rates are higher at the same relative intensity when you wear a mask.” Some people also could experience lightheadedness during familiar workouts while masked, says Len Kravitz, a professor of exercise science at the University of New Mexico.

What is pandemic paid leave?

The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.

“The push-pull of that committee is palpable,” she said. “As everyone knows, if you ask a committee to design a horse, you get a camel.”

Airborne transmission is the most likely explanation for several clusters of infection, including a choir in Washington State and a restaurant in China, according to some scientists.

But W.H.O. staff members have yet to accept the importance of these case studies and instead have “dreamed up an alternative story” in which an infected person spat on his hands, wiped it on something and “magically” infected numerous other people, Dr. Greenhalgh said.

The agency’s staff and nearly 30 volunteer experts have spent weeks reviewing evidence on the possible modes of transmission: by exhalation of large and small droplets, for example, by contact with a contaminated surface, or from a mother to her baby.

The W.H.O. easily accepts that droplet and fomite transmission occur, but seems to want more definitive proof of spread by aerosols, some experts said. The agency has noted that the virus has not been cultured from air samples, for example, but the same was true of influenza for many years until two groups of scientists figured out how to do it, noted Don Milton, an aerosol expert at the University of Maryland.

W.H.O. staff members are reluctant to make statements when they do not have irrefutable proof of certain phenomena, and are slow to update their hypotheses, scientists have charged. “They are still challenged by the absence of evidence, and the difficulty of proving a negative,” Dr. Hanage said.

“The W.H.O. is being overly cautious and shortsighted unnecessarily,” Dr. Julian W. Tang, honorary professor of respiratory sciences at the University of Leicester in the United Kingdom, said in an email.

“By recognizing aerosol transmission of SARS-CoV-2 and recommending improved ventilation facilities to be upgraded or installed, you can improve the health of people” by eliminating a variety of hazards, including indoor pollutants and allergens, he added.

“Isn’t that what the W.H.O. stands for — the improvement of human health from all angles?”

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