This article is from the source 'nytimes' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.
You can find the current article at its original source at https://www.nytimes.com/2020/07/09/health/virus-aerosols-who.html
The article has changed 24 times. There is an RSS feed of changes available.
| Version 4 | Version 5 |
|---|---|
| The Coronavirus Can Be Airborne Indoors, W.H.O. Says | The Coronavirus Can Be Airborne Indoors, W.H.O. Says |
| (6 days later) | |
| The coronavirus may linger in the air in crowded indoor spaces, spreading from one person to the next, the World Health Organization acknowledged on Thursday. | The coronavirus may linger in the air in crowded indoor spaces, spreading from one person to the next, the World Health Organization acknowledged on Thursday. |
| The W.H.O. had described this form of transmission as doubtful and a problem mostly in medical procedures. But growing scientific and anecdotal evidence suggest this route may be important in spreading the virus, and this week more than 200 scientists urged the agency to revisit the research and revise its position. | The W.H.O. had described this form of transmission as doubtful and a problem mostly in medical procedures. But growing scientific and anecdotal evidence suggest this route may be important in spreading the virus, and this week more than 200 scientists urged the agency to revisit the research and revise its position. |
| In an updated scientific brief, the agency also asserted more directly than it had in the past that the virus may be spread by people who do not have symptoms: “Infected people can transmit the virus both when they have symptoms and when they don’t have symptoms,” the agency said. | In an updated scientific brief, the agency also asserted more directly than it had in the past that the virus may be spread by people who do not have symptoms: “Infected people can transmit the virus both when they have symptoms and when they don’t have symptoms,” the agency said. |
| The W.H.O. previously said asymptomatic transmission, while it may occur, was probably “very rare.” | The W.H.O. previously said asymptomatic transmission, while it may occur, was probably “very rare.” |
| Some experts said both revisions were long overdue, and not as extensive as they had hoped. | Some experts said both revisions were long overdue, and not as extensive as they had hoped. |
| “It is refreshing to see that W.H.O. is now acknowledging that airborne transmission may occur, although it is clear that the evidence must clear a higher bar for this route compared to others,” Linsey Marr, an aerosol expert at Virginia Tech, said in an email. | “It is refreshing to see that W.H.O. is now acknowledging that airborne transmission may occur, although it is clear that the evidence must clear a higher bar for this route compared to others,” Linsey Marr, an aerosol expert at Virginia Tech, said in an email. |
| An aerosol is a respiratory droplet so small it may linger in the air. In its latest description of how the virus is spread, the agency said transmission of the virus by aerosols may have been responsible for “outbreaks of Covid-19 reported in some closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking or singing.” | An aerosol is a respiratory droplet so small it may linger in the air. In its latest description of how the virus is spread, the agency said transmission of the virus by aerosols may have been responsible for “outbreaks of Covid-19 reported in some closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking or singing.” |
| The W.H.O. had maintained that airborne spread is only a concern when health care workers are engaged in certain medical procedures that produce aerosols. But mounting evidence has suggested that in crowded indoor spaces, the virus can stay aloft for hours and infect others, and may even seed so-called superspreader events. | The W.H.O. had maintained that airborne spread is only a concern when health care workers are engaged in certain medical procedures that produce aerosols. But mounting evidence has suggested that in crowded indoor spaces, the virus can stay aloft for hours and infect others, and may even seed so-called superspreader events. |
| The agency still largely emphasizes the role played by larger droplets that are coughed or inhaled, or by contact with a contaminated surface, also called a fomite. And in a longer document detailing scientific evidence, the W.H.O. still maintained that “detailed investigations of these clusters suggest that droplet and fomite transmission could also explain human-to-human transmission.” | The agency still largely emphasizes the role played by larger droplets that are coughed or inhaled, or by contact with a contaminated surface, also called a fomite. And in a longer document detailing scientific evidence, the W.H.O. still maintained that “detailed investigations of these clusters suggest that droplet and fomite transmission could also explain human-to-human transmission.” |
| In addition to avoiding close contact with infected people and washing hands, people should “avoid crowded places, close-contact settings, and confined and enclosed spaces with poor ventilation,” the agency said, and homes and offices should ensure good ventilation. | In addition to avoiding close contact with infected people and washing hands, people should “avoid crowded places, close-contact settings, and confined and enclosed spaces with poor ventilation,” the agency said, and homes and offices should ensure good ventilation. |
| These recommendations are “what is needed to help slow transmission in communities,” Dr. Marr said. | These recommendations are “what is needed to help slow transmission in communities,” Dr. Marr said. |
| There is debate about the relative contribution of airborne spread, compared with transmission by droplets and surfaces. The new brief still skirts that question. | There is debate about the relative contribution of airborne spread, compared with transmission by droplets and surfaces. The new brief still skirts that question. |
| “I interpret this as saying, ‘While it is reasonable to think it can happen, there’s not consistent evidence that it is happening often,’” Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, said in an email. | “I interpret this as saying, ‘While it is reasonable to think it can happen, there’s not consistent evidence that it is happening often,’” Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, said in an email. |
| After The Times reported that an international group of 239 experts planned to call on the W.H.O. to review the research, Dr. Benedetta Allegranzi, head of the agency’s infection prevention and control committee, said on Tuesday that the possibility of airborne spread in “crowded, closed, poorly ventilated settings” could not be ruled out. | After The Times reported that an international group of 239 experts planned to call on the W.H.O. to review the research, Dr. Benedetta Allegranzi, head of the agency’s infection prevention and control committee, said on Tuesday that the possibility of airborne spread in “crowded, closed, poorly ventilated settings” could not be ruled out. |
| Outdoors, any virus in small or large droplets may be diluted too quickly in the air to pose a risk. But even a small possibility of airborne spread indoors has enormous implications for how people should protect themselves. | Outdoors, any virus in small or large droplets may be diluted too quickly in the air to pose a risk. But even a small possibility of airborne spread indoors has enormous implications for how people should protect themselves. |
| People may need to minimize time indoors with others from outside the household, in addition to maintaining a safe distance and wearing cloth face coverings. Businesses, schools and nursing homes may need to invest in new ventilation systems or ultraviolet lights that destroy the virus. | People may need to minimize time indoors with others from outside the household, in addition to maintaining a safe distance and wearing cloth face coverings. Businesses, schools and nursing homes may need to invest in new ventilation systems or ultraviolet lights that destroy the virus. |
| Some experts have criticized the W.H.O. for being slow to acknowledge the possibility of airborne spread while emphasizing hand washing as the primary preventive strategy. Even in the new brief, it’s clear that members of the committee interpreted the evidence differently, said Dr. Trish Greenhalgh, a professor of primary health care at the University of Oxford. | Some experts have criticized the W.H.O. for being slow to acknowledge the possibility of airborne spread while emphasizing hand washing as the primary preventive strategy. Even in the new brief, it’s clear that members of the committee interpreted the evidence differently, said Dr. Trish Greenhalgh, a professor of primary health care at the University of Oxford. |
| Updated July 15, 2020 | |
| 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. | |
| 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. | |
| 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. | |
| 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. | |
| The steroid, dexamethasone, is the first treatment shown to reduce mortality in severely ill patients, according to scientists in Britain. The drug appears to reduce inflammation caused by the immune system, protecting the tissues. In the study, dexamethasone reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth. | |
| 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. | |
| 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. | |
| Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks. | |
| A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study. | |
| If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.) | |
| If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others. | |
| “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.” | “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. | 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. | 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. |
| [Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.] | [Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.] |
| 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 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. | 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. | 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. | “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. | “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?” | “Isn’t that what the W.H.O. stands for — the improvement of human health from all angles?” |