The CDC says the coronavirus is spread mainly through respiratory aerosols

The CDC says the coronavirus is spread mainly through respiratory aerosols

The coronavirus spreads more often in the air, through droplets or other tiny respiratory particles that can apparently remain suspended and inhaled, according to new guidance from the Centers for Disease Control and Prevention.

Smaller particles, known as aerosols, are produced when an infected person coughs, sneezes, sings, speaks or breathes and can inhale into someone’s nose, mouth, airways or lungs, according to the CDC, which generally says , indoors Settings without good ventilation increase the risk of transmission.

“It is considered to be the main way the virus has spread,” the CDC said posted on its website. “There is growing evidence that droplets and airborne particles may remain suspended in the air and breathe by others and travel more than six feet (for example, during a choir, restaurant or gym class).”

Aerosol and Koranovirus experts say the change is a profound change in understanding how the virus, which has caused nearly 200,000 lives in the United States, is spreading. However, the updated two-page explanation provided some new guidance on how to protect against airborne transmission.

Previously, the said the federal health agency The virus is spread mainly among people who are about six meters away from each other and through the direct passage of exhaled droplets that land on the noses and mouths of people nearby. The CDC has also said – and continues to say – that people can become infected by touching something that has the virus and then touching their mouth, nose or eyes, but this touch is not the main way it is spread.

Researchers studying the transmission of the deadly virus observed the new guidance on Sunday on the CDC website, which was marked as an update from Friday. As with some other updates, the CDC made major changes to its guidance without issuing a notice.

The CDC did not respond to requests for information on Sunday.

According to the guidance, the CDC website states that in addition to using a mask, washing hands and staying “at least six feet away” from others, people should stay home and isolate themselves when they are sick and ” use air purifiers to reduce airborne germs. Previously, the advice was to maintain a “good social distance” of “about six feet”.

The CDC and the World Health Organization have long resisted the idea that the coronavirus spreads more than six feet through the air, with the WHO initially claiming that airborne transmission only occurred during certain medical procedures. But in July, under increasing pressure from researchers, the WHO acknowledged that the virus could remain in the air indoors and possibly infect humans. even when exercising social distances.

Aerosol scientists have found evidence – including “spread” events such as choir practices that infected many people – that the virus can be spread through tiny respiratory particles. This week, the scientific journal Indoor Air received one paper for a post that found that many of the 53 choir singers who got sick After attending a March 10 practice at Mount Vernon, Washington, he probably caught COVID-19 via airborne transmission.

Jose-Luis Jimenez, an aerosol scientist at the University of Colorado Boulder and one of the authors of this report, said in an interview Sunday that the CDC’s updated guidance represented a major change. So far, he said, the agency’s scientists have said the virus is transmitted through the air when droplets are fired from a person’s mouth or nose in the form of a projectile, directly infecting another person.

“They changed it and did not tell anyone,” he said.

Donald Milton, a professor of environmental health at the University of Maryland and an aerosol specialist, said in an interview Sunday that the CDC has gradually come to terms with airborne transmission as data has accumulated, noting that the agency has made sudden changes to its guidance in the past.

“They have paid attention and are moving in response to the investigation, so I am glad to see that they are continuing and that no one is stopping,” he said.

Unannounced in May, the CDC changed its guidance on opening houses of worship, deleting a warning issued the previous day that the act of singing could contribute to the transmission of coronaviruses – a switch reportedly due to White House pressure. Friday’s updated guidance described the song as one of the activities that could produce contaminating aerosols.

Jimenez and Milton said it was important to wear masks to reduce the risk of COVID-19 spreading and contracting. They said it was important to make sure the face masks fit properly so that the aerosols would not escape or enter through gaps in the mask around the nose or mouth.

“Aerosols can travel farther than six feet, but they are more concentrated as you approach, so staying as far away as possible reduces the risk,” Milton said. “The reason bars were such a big problem is that people get stronger when they drink alcohol and move around to listen and you can’t drink a beer or a masked shot.”

Milton and Shelley Miller, another aerosol researcher at the University of Colorado Boulder, is studying ways in which wind instrument singing and playing can be made safer by distance, ventilation and coverage with different types of materials. The research is funded by national choir and organ associations whose members were unable to gather during the pandemic.

Good ventilation reduces the risk indoors, as does opening windows to allow air to circulate, the researchers said. Roof units that use ultraviolet light to kill the virus also show promise, they said.

Milton and Jimenez were among a team of researchers who wrote an open letter to the WHO, which eventually signed 239 researchers from 32 countries, who called on officials to accept the possibility that aerosols could play an important role in spreading the virus. The WHO revised its guidelines after receiving the letter on July 6, stating that airborne transmission had not been definitively proven, but advised people to avoid poorly ventilated areas.

The CDC has now taken another important step in recognizing the role of aerosols, Jimenez said.

“The whole field of aerosol science tells them that the understanding of ballistic droplets is outdated and they are real aerosols that spread the virus,” he said.

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