In a new study, researchers found that the virus can travel up to 26 feet of breath drops in a few seconds after coughing, sneezing, or singing.
The 6-foot guidance is based on an oversimplified scenario that looks at how viruses are moved by large or small aerial droplets without accounting for other factors. The transmission of the virus is more complex. This includes the range of small droplets and virus-inducing activity through the air. The research team evaluated published studies that found that respiratory droplets from coronoviruses that could spread under different conditions from COVID-19, as well as other viruses.
Based on those findings, they suggest that a better model for guiding social distance is needed. Guidelines should consider the setting, how crowded it is, how long someone is there and whether people are covering the face. Using that guide, a poorly ventilated, crowded environment where people are screaming and singing and not covering the face would be high risk. And an outdoor, well-ventilated, less crowded environment, where people remain calm and face covered, is less risky.
Taking these factors into account for adjusting social disturbance guidelines would mean greater safety in high-risk settings, but greater freedom in low-risk settings – and a return to “normal” at least in some situations.
Their bottom line: The best social disturbances depend on many things that combine to determine the risk of virus transmission.
“It’s easy to understand that there’s a quick-easy rule of thumb for ‘how close it is,’ but biology is much more complicated than that,” says Kristin Breton Nelson, PhD, assistant professor of epidemiology at Emory University in Atlanta Rollins School of Public Health. He has researched the superseding of COVID-19 in Georgia.
He agrees with the researchers that the recommendations should reflect that nuance and provide clear guidance about the highest-risk activities.
Len Horowitz, MD, a lung specialist at Lenox Hill Hospital in New York City, says you have to think about the risk of COVID transmission like smoking. “When you take out the cigarette smoke, you can see that it is more than 6 feet away.”
The transmission risk of COVID-19 depends greatly on the circumstances, says Horowitz, who were not included in the study. “Indoor is more risky than outdoor.” Particle size matters, he says. “If it’s small, it can travel fast.” The risk, he says, “depends on your activity, the wind speed in the room, the humidity and how long you’ve actually been in the room.” Viral load – or virus levels within a person’s airway – also varies from person to person, they say.
He encourages people to consider all these things when deciding on the amount of social disturbances. “If you’re wearing a mask, not screaming, not sick, keep your mask on, and have some indoor ventilation. 6 This is usually enough.”
Bretton Nelson agrees that there is a limit to the risk of transmission.
It is important to keep in mind that not only how far you need to stay away from others while physically thinking, but also think about which activities are safe.
“It’s not ‘safe’ and ‘not safe,” she says, but by establishing which activities and environments are the safest, people can try to focus on them.