“We’re having surprises all the way,” Dr. Conly said. “In this paper I find it interesting, but I still have to go so I can get into a line of credibility.”
Dr. George Rutherford, a professor of epidemiology at the University of California, San Francisco, was similarly skeptical. He said that, outside of hospital settings, “big drops in my mind account for the vast majority of cases. Aerosol transmission – if you really work with that, it creates a lot of dissonance. Are there situations where there may be? Yes maybe, but it’s a small amount. “
Dr. Tang and other scientists disagree. “If I’m talking to an infected person for 15 or 20 minutes and to get some air out of them,” Dr. Tang said, “isn’t that a simpler way to explain transmission than touching an infected face and touching your eyes? When you’re talking on an outbreak, as in a restaurant, the latter seems to be a torturous way of explaining the transmission. “
Coronavirus Outbreak ›
Frequently Asked Questions
Updated July 27, 2020
Do I have to refinance my mortgage?
- It may be a good idea, because mortgage rates have never been lower. Refinancing demands have forced mortgage applications to some of the highest levels since 2008, so be prepared to comply. But the shortcomings are also high, so if you are thinking of buying a home, be aware that some lenders have tightened their standards.
What does school look like in September?
- Many schools are unlikely to return to a normal schedule this autumn, requiring the grinding of online learning, the care of children they do quickly and the restless working day. California’s two largest public school districts – Los Angeles and San Diego – said on July 13 that instruction will only be done remotely in the fall, and expressed concern that the increase of coronavirus infections in their areas can be a very difficult risk for students and teachers. Together, the two districts enroll about 825,000 students. They are the largest in the country so far to abandon plans for a partial physical return even in classes when they reopen in August. For other districts, the solution would not be an all or nothing approach. Many systems, including the largest nation, New York City, are drawing up hybrid plans that involve spending some days in classes and other days online. There is still no national policy on this, so check your municipal school system regularly to see what is happening in your community.
Is the coronavirus in the air?
- The coronavirus can sit aloft for hours in small drops in stagnant air, infecting people as they breathe, and suggests scientific evidence. This risk is highest in poorly ventilated crowded indoor spaces, and can help explain the super-widespread events reported in cardboard plants, churches and restaurants. It is unclear how often the virus spreads through these small droplets, or aerosols, compared to large droplets that are expelled when a sick person observes or sneezes, or is transmitted through contact with contaminated surfaces, he said. Linsey Marr, aerosol expert at Virginia Tech. Aerosols are released even when an asymptomatic person sneezes, talks or sings, according to Dr. Marr and more than 200 other experts, who drafted the evidence in an open letter to the World Health Organization.
What are the symptoms of coronavirus?
Does asymptomatic transmission of Covid-19 occur?
- So far, the evidence seems to show so. A highly-cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and an estimate that 44 percent of new infections were the result of transmission from people who have not yet been infected. did not show symptoms. Recently, a leading expert at the World Health Organization stated that transmission of coronavirus by asymptomatic people was “very rare,” but later reversed that statement.
In the new analysis, a team led by Parham Azimi, an indoor air researcher at Harvard’s TH Chan School of Public Health, studied the outbreak on Princess Diamond, where physical spaces and infections were well documented. He ran more than 20,000 simulations of how the virus could have spread throughout the ship. Each simulation made a variety of assumptions, about factors such as patterns of social interaction – how much time people spend in their booths, on the deck or in the cafeteria, on average – and the amount of time the virus can live on surfaces. Each also considered in various contributions of small, floating droplets, broadly defined as 10 microns or smaller; and larger drops, which fall faster and infect other faces or people, by falling on their eyes, mouth or nose, they say.
About 130 of those simulations reproduced, to some extent, what actually happened to the Princess of Diamonds as she burst. By analyzing these most “realistic” scenarios, the research team calculated the most likely contributions of each transmission route. The researchers concluded that small drops predominated, accounting for about 60 percent of new infections above all, both in nearby locations, in a few yards of an infected person, and at greater distances.
“A lot of people have argued that airborne transmission is happening, but no one had numbers for that,” Azimi said. “What is the contribution from these small drops – is it 5 percent, or 90 percent? In this paper, we provide the first real estimates for what that number might be, at least in the case of this cruise ship. “
The logic behind this transmission is simple, experts said. When a person speaks, he or she emerges from a cloud of drops, the vast majority of which are small enough to remain suspended in the air for a few minutes or longer. By inhalation, those small droplet clouds are more likely to reach a mucous membrane than larger ones that ballistically rise.