CDC says coronavirus can spread more than 6 feet through aerosols

The top U.S. public health agency said Monday that the coronavirus can spread more than 6 feet through the air, especially in poorly ventilated and enclosed spaces. But agency officials maintained that such spread is uncommon and current social distancing guidelines still make sense.

However, several experts faulted the updated Centers for Disease Control and Prevention guidance. They said the virus can spread more easily than the CDC seems to be indicating, and suggested that the public should wear masks even in prolonged outdoor gatherings when they are more than 6 feet apart.

The virus “is traveling through the air and there is no bright line. You’re not safe beyond 6 feet. You can’t take your mask off at 6 feet,” said Dr. Donald Milton of the University of Maryland School of Public Health.

For months, the CDC has said that the virus spreads mainly through small airborne droplets when an infected person coughs or sneezes. Most CDC guidance about social distancing is built around that idea, saying that 6 feet is a safe buffer between people who are not wearing masks.

In interviews, CDC officials have also acknowledged growing evidence that the virus can sometimes spread on even smaller particles called aerosols that spread over a wider area.

In the update posted on its website, the agency again acknowledged recent research showing people with COVID-19 infected others who were more than 6 feet away or shortly after an infected person left an area. CDC officials called those ”limited, uncommon circumstances.”

In those cases, spread occurred in poorly ventilated and enclosed spaces where people were doing activities that caused heavier breathing, like singing or exercise, CDC officials said.

People can protect themselves by staying at least 6 feet away from others, wearing a mask, washing their hands, cleaning touched surfaces and staying home when sick

Last month, the CDC ignited controversy among experts when it quietly posted an update that seemed to suggest the agency’s position had changed, and then within days took it down again.

The short-lived post said the virus can remain suspended in the air and drift more than 6 feet, and officials emphasized the importance of indoor ventilation. It also added singing and breathing to the ways the virus can go airborne.

Federal health officials later said the post was a mistake and that it had been released before full editing and clearance was completed. They said there was no major change in the agency’s position, but they would finalize a post to clarify the CDC’s thinking. That’s what was posted Monday.

A small group of researchers—including Milton—on Monday published a letter in the journal Science that called for clearer public health guidance about how coronavirus spreads in the air.

They said health officials need to use clearer language in talking about the size of airborne particles and droplets that can spread the disease, and be more straightforward about the role that viruses in small aerosols can play in infecting people.

Masks and good ventilation are crucial indoors. But they can be important outdoors too, said Linsey Marr of Virginia Tech.

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3 thoughts on “CDC says coronavirus can spread more than 6 feet through aerosols

  1. No wonder we are struggling with containing this virus – the CDC still can’t decide how/when/where it can be spread. First they said no masks needed. Then they said masks. Then it lived on surfaces for a week, then it did not. Then it was 14 days of quarantine, now its 10 days of isolation. Different words/different meanings? Can you just do the full research and definitively be straight with the public exactly what it is – so that the politics of fear can be avoided and we can address solutions and get on with it?

    1. “Can you just do the full research and definitively be straight with the public exactly what it is”

      ‘Full research’ takes time. If looking to wait for definitive guidelines, we’d be waiting until at least 2022… The CDC has updated guidance as they’ve learned more, but it is a balancing act between confidence and risk to the public, where there are no bright lines. Is “no risk” set at 5% chance? 1%? .01% – compound that with a ton of variables, such as length of exposure, distance, intensity, exposed person’s health, just as starters. The best the CDC can do right now is to advice more/less risky, and degrees of those differences. and they’ve mostly done that. Revision from 14 days to 10 days makes sense. (the less known at the beginning, the wider margin for error you take – the more that is known, the tighter the guidelines can be)

  2. CDC nor others do not know the full impact at this time. Individuals are left to their best judgment which does not seem that difficult. Use a mask and social distances. Is the room poorly ventilated, crowded, and readily characterized by loud conversations – if so, then perhaps one should leave. Perhaps one is luxuriating in a crowded park within the highly touted 6 foot distance; however, a prevailing slight breeze may move the airborne particles farther – this circumstance may lead one to reach for the mask. Absolute definitive finding do not yet exist; research continues. And the virus continues to mutate. To err on the conservative side, one can wear a mask and seek to minimize contact with others.

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