The Centers for Disease Control and Prevention are clear and consistent in their recommendation on social distancing: To reduce the risk of contracting the coronavirus, people should stay at least two meters away from other people who are not in their household. The guideline applies whether you are eating in a restaurant, lifting weights in a gym, or studying long divisions in a fourth grade classroom.
The directive was particularly momentous for schools, many of which have not fully reopened because they do not have enough space to keep students two meters apart.
Spurred on by a better understanding of how the virus is spreading and growing concerns about the harm caused by keeping children away from school, some public health experts are calling on the agency to reduce the recommended distance in schools from two meters to three.
“I never noticed that six feet are particularly useful in the context of mitigation,” said Dr. Ashish Jha, dean of Brown University School of Public Health. “I wish the CDC would just come out and say this isn’t a big problem.”
On Sunday, Dr. Anthony S. Fauci, the director of the National Institute for Allergies and Infectious Diseases, said on CNN that the CDC was up Review of the matter.
The idea remains controversial, in part because few studies have directly compared different distancing strategies. But the issue also boils down to a devilishly difficult and often personal question: How safe is safe enough?
“There is no magical limit for any distance,” says Dr. Benjamin Linas, an infectious disease specialist at Boston University. “There’s a risk at six feet, there’s a risk at a meter, there’s a risk at nine feet. There is always a risk. ”He added,“ The only question is, how much is the risk? And what do you give up for it? “
The origins of six feet
The origin of the recommendation to distance a distance of two meters is a mystery. “It’s almost like it came out of nowhere,” said Linsey Marr, a virus transmission expert at Virginia Tech University.
When the virus first emerged, many experts believed that it was mainly transmitted through large respiratory droplets that are relatively heavy. Ancient scientific studies, some dating back more than a century, suggested that these droplets tend not to travel more than 1 to 2 meters. That observation, plus an abundance of caution, may have led the CDC to make their six-foot-tall proposal, said Dr. Marr.
But this recommendation was not universal. The American Academy of Pediatrics recommends three to six feet of social distancing in schools, but the World Health Organization recommends only one meter, or 3.3 feet.
And in the last year, scientists have learned that respiratory droplets are not the primary route of transmission of the coronavirus. Instead, the virus mainly spreads through tiny droplets in the air known as aerosols, which can travel long distances and flow through rooms in unpredictable ways.
The data also suggest that schools appear to be relatively low-risk environments; Children under the age of 10 seem to be less likely to transmit the virus than adults.
There has been evidence in recent months that schools may not require two meters of space. Case numbers were generally low, even in schools with looser distancing guidelines. “We know that many schools are open to less than six feet and have not experienced major outbreaks,” said Dr. Yeh.
In a 2020 analysis of observational studies in a variety of settings, researchers found that a physical distance of at least one meter significantly reduced transmission rates of several different coronaviruses, including the one that causes Covid-19. However, they found some evidence that a two-meter guideline “might be more effective”.
July 6, 2021, 6:47 p.m. ET
“One of the really important data points that has been missing so far is a head-to-head, head-to-head comparison of locations that introduced a meter by six feet apart,” said Dr. Elissa Perkins, the director of emergency medicine for infectious disease management at Boston University School of Medicine.
Dr. Perkins and her colleagues recently performed such a comparison using a natural experiment in Massachusetts. Last summer, the state’s Department of Education issued guidelines recommending three to six feet of clearance in schools that should reopen in the fall. As a result, school policies varied: some districts required a strict distance of two meters while others only required three. (The state required all staff and students from the second grade to wear masks.)
The researchers found that the social distancing strategy had no statistically significant impact on Covid-19 case rates, the team reported in the journal Clinical Infectious Diseases last week. The study also found that Covid-19 rates in schools were lower than in surrounding communities.
The authors say the results are reassuring that schools can relax their distance regulations and still be safe, provided they take other precautions, like wearing universal masks.
“The masking still appears to be in effect,” said lead investigator Dr. Westyn Branch-Elliman, an infectious disease specialist with the VA Boston Healthcare System. “And if we have universal masking mandates, I think it is very sensible to move on to a one and a half meter high recommendation.”
Not everyone finds the study so convincing. A. Marm Kilpatrick, an infectious disease researcher at the University of California, Santa Cruz, said the school district’s data was too noisy to draw any firm conclusions. “It doesn’t really allow you to get an answer that you can really feel confident about,” he said.
The study’s authors admitted they couldn’t rule out the possibility that increased distancing provided a small benefit.
In the case of aerosol transmission, safety generally increases with distance; the further the aerosols travel, the more dilute they are. “It’s like being close to a smoker,” said Dr. Marr. “The closer you are, the more you will breathe in.”
Apart from the distance: the more people there are in a room, the higher the likelihood that one of them will contract the coronavirus. A 6-foot rule helps reduce that risk, said Donald Milton, an aerosol expert at the University of Maryland: “When people are three feet apart, you can’t wrap them up. And so it’s safer just because it’s less dense. ”
Masks and good ventilation go a long way in reducing the risk. With these measures, the difference between three and six feet is likely to be relatively small, scientists said. And unless Covid-19 is very common in the surrounding community, the absolute risk of contracting the virus in schools is likely to remain small as long as these protections are in place.
“We can always do something to further reduce our risks,” said Dr. Marr. “But at some point you get falling returns and you have to think about the cost of achieving these additional risk reductions.”
Debate and Risk Mitigation
Some experts say a small increase in risk is outweighed by the benefits of fully reopening schools. “Trying to follow the two-meter-long guideline shouldn’t prevent us from bringing children back to school all day long with masks on and at least three feet apart,” said Dr. Marr.
Others said it was too early to relax CDC guidelines. “Ultimately, I think there might be a place for this changing guide,” Saskia Popescu, an infectious disease epidemiologist at George Mason University, said in an email. “But not now, when we struggle to vaccinate people, we are still seeing over 60,000 cases a day trying not to reverse the progress we’ve made.”
Even advocates of changing the guideline say that any transition to looser detachment must be made carefully and in combination with other precautionary measures. “If you are in an area where there is not a strong tendency to rely on masks, I don’t think it advisable to extrapolate our data to that environment,” said Dr. Perkins.
In addition, officials risk tampering with public health messages by setting different standards for schools than other common spaces. “I’ve developed on it,” said Dr. Linas. “Last summer I thought, ‘How are we going to explain to people that it’s six feet everywhere but in schools? That doesn’t seem consistent and problematic. ‘”
But schools are unique, he said. They are relatively controlled environments that can enforce certain security measures, and they have unique benefits to society. “The advantages of school are different from those of cinemas or restaurants,” he said. “So I’d be willing to take a little more risk just to keep it open.”