Is 6 feet far enough? Study suggests coronavirus can leap the social distancing gap

The Centers for Disease Control and Prevention recommend people stand six feet away from one another to avoid spreading the coronavirus. But research suggests that is not nearly enough distance to keep yourself safe from the coronavirus.

Social distancing measures encourage people to either stay home or, in cases when you need to go out in public, keep a safe distance, according to CDC guidelines. But research suggests that safe distance is actually 27 feet, USA Today reported.

Research on the dynamics of coughs and sneezes found these “exhalations cause gaseous clouds” that have the ability to travel up to 27 feet, Dr. Lydia Bourouriba, an associate professor at MIT, told USA Today.

But Dr. Anthony Fauci, the nation’s top infectious disease expert, said in a press conference Tuesday that he was skeptical of the report and suggested it is “terribly misleading,” according to the New York Post.

Fauci added it would have to be a “very, very robust, vigorous, achoo sneeze” to spread that far, according to the New York Post.

Bourouiba wrote in the Journal of the American Medical Association that the social distancing measures in place now are based on a model of disease transmission developed in the 1930s.

“Implementing public health recommendations based on these older models may limit the effectiveness of the proposed interventions,” Bourouiba wrote in the study published March 26.

The World Health Organization says respiratory infections are spread through droplets of different sizes, and the coronavirus is no different. Droplets are transmitted when someone coughs or sneezes into the air, according to WHO.

William F. Wells, who studied Tuberculosis transmission in the 1930s, categorized those droplets as large and small, Bourouiba writes. The large droplets settle fast, but small droplets – also referred to as aerosols - evaporate and “form residual particulates made of the dried material from the original droplets,” according to Bourouiba.

“Infection control strategies were then developed based on whether a respiratory infectious disease is primarily transmitted via the large or the small droplet route,” Bourouiba wrote.

That droplet size classification system is what the WHO and CDC base their recommendations on, but that might explain the rapid international spread of coronavirus, Bourouiba said.

Bourouiba’s research demonstrates that sneezes and coughs consist of gas clouds that carry clusters of droplets. Existing in this gas cloud allows droplets to avoid evaporation longer than singular droplets, Bourouiba wrote.

“Under these conditions, the lifetime of a droplet could be considerably extended by a factor of up to 1000, from a fraction of a second to minutes,” she said.

How far can coronavirus germs travel?

Dr. Paul Pottinger, an infectious disease professor at the University of Washington School of Medicine, said if Bourouiba’s research was accurate, more people would be sick, USA Today reported.

“If you think about it, if this really traveled very efficiently by air, we wouldn’t be having this conversation. Everybody would know it’s true because everybody would be infected,” Pottinger told USA Today. “If it was a 27-foot radius that was a high risk to somebody, this would be a totally different conversation. It’s not.”

But the WHO recognizes that in the context of coronavirus, “airborne transmission may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed.”

Bourouiba’s research also cites a 2020 report from China that showed COVID-19 particles were found in the hospital ventilation systems above rooms where patients had coronavirus.

“Finding virus particles in these systems is more consistent with the turbulent gas cloud hypothesis of disease transmission than the dichotomous model because it explains how viable virus particles can travel long distances from patients,” Bourouiba wrote.

The study done by a team of Chinese government epidemiologists shows that COVID-19 “can linger in the air for at least 30 minutes and travel up to 4.5 meters,” or a little over 14 feet, the South China Morning Post reported.

“It can be confirmed that in a closed environment with air-conditions, the transmission distance of the new coronavirus will excee the commonly recognised distance,” the researchers wrote in an article published in Practical Preventive Medicine, according to the South China Morning Post.

Bourouiba argues that agencies should be overly cautious when considering social distancing measures, even if the scientific community can’t agree on a specific distance that the coronavirus can travel.

“Although there remains a lot of questions to be addressed about how much virus is at a given distance or not, we have no answer one way or another at this time,” Bourouiba told USA Today. “Therefore, the precautionary principle should drive the policies to state that we should have high-grade respirators used for health care workers.

This story was originally published March 31, 2020 at 6:58 PM with the headline "Is 6 feet far enough? Study suggests coronavirus can leap the social distancing gap."