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 three feet away from other people who are not in their households . The guideline applies whether you’re eating in a restaurant, lifting weights in a gym, or studying a long pitch in a fourth grade classroom.
The directive was particularly relevant to schools, many of which have not fully reopened because they do not have enough space to keep students three feet apart.
With a better understanding of the spread of the virus and growing concerns about the harm caused by keeping children out of school, some public health experts are calling on the agency to reduce the recommended distance in schools from six feet to three feet .
“I’ve never noticed that six feet is particularly sensual for the purposes of damage control,” 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 Allergy and Infectious Diseases, said on CNN that the CDC was up Review the matter.
The idea remains controversial, also because few studies have directly compared different distancing strategies. But the problem also boils down to a devilishly difficult and often personal question: How safe is safe enough?
“There is no magical threshold for any distance,” said Dr. Benjamin Linas, an infectious disease specialist at Boston University. “There’s a risk at six feet, there’s a risk at three feet, there’s a risk at nine feet. There is always a risk. “He added,” The question is, what is the risk. And what do you give up for it? “
The origins of six feet
The origin of the six foot long distancing recommendation is a mystery. “It’s almost like it was pulled out of nowhere,” said Linsey Marr, a virus transmission expert at Virginia Tech University.
When the virus first appeared, 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 did not travel more than three to six feet. That observation, plus an abundance of caution, may have led the CDC to make their six-foot-long proposal, said Dr. Marr.
However, 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 over the past year, scientists have learned that respiratory droplets are not the primary mode of coronavirus transmission. Instead, the virus mainly spreads through tiny droplets in the air known as aerosols. These can travel long distances and flow through rooms in unpredictable ways.
Data also suggest that schools appear to be a relatively low risk environment. 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 school may not require six feet of distance. Fall rates were generally low even in schools with loose distancing policies. “We know that many schools are less than six feet open and have not seen large outbreaks,” said Dr. Yeh.
March 16, 2021, 7:09 p.m. ET
In a 2020 analysis of observational studies in different environments, the researchers found that a physical distance of at least a meter significantly reduced the transmission rates of several different coronaviruses, including those that cause Covid-19. However, they found evidence that a two-meter guideline “might be more effective”.
“One of the really important data points that have been missing is a head-to-head, head-to-head comparison of locations that have been implemented three feet apart with six feet apart,” said Dr. Elissa Perkins, director of Infectious Diseases in Emergency Medicine 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 away in schools due to reopen in the fall. As a result, school policies were different: some districts enforced a strict six-foot distancing while others only required three. (The state required all staff, as well as second-grade students and above, 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 reassure schools that schools can relax their distancing requirements and still be safe, provided they take other precautions, such as enforcing wearing a universal mask.
“The masking still appears to be effective,” said lead investigator Dr. Westyn Branch-Elliman, an infectious disease specialist with the VA Boston Healthcare System. “Assuming we have universal masking mandates, I think it very sensible to move to a three-foot recommendation.”
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Not everyone finds the study so convincing. A. Marm Kilpatrick, an infectious disease researcher at the University of California at Santa Cruz, said the school district’s data was too loud to draw any definitive 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 that they couldn’t rule out that increased distancing was of little benefit.
With aerosol transfer, safety generally increases with distance. The further the aerosols move, the more dilute they become. “It’s like being near a smoker,” said Dr. Marr. “The closer you are, the more you will breathe in.”
And apart from the distance, the more people there are in a room, the higher the likelihood that one of them will get infected with the coronavirus. A six-foot rule helps reduce that risk, said Donald Milton, aerosol expert at the University of Maryland: “When people are six feet apart, you can’t wrap them up. 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 should be relatively small, scientists said. And if Covid-19 isn’t very common in the surrounding community, the absolute risk of contracting the virus in schools is likely to remain small as long as that protection is in place.
“There is always something we can do to further reduce our risks,” said Dr. Marr. “But at some point you will see declining returns and you will have to think about the cost of trying to achieve these additional risk reductions.”
Debate and Risk Reduction
Some experts say a small increase in risk will be outweighed by the benefits of fully reopening schools. “Trying to follow the 6-foot guideline shouldn’t prevent us from bringing children back to school full-time with masks at least 3 feet away,” 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 it’s not now when we’re struggling to vaccinate people we’re still seeing over 60,000 cases a day and we’re trying not to reverse the advances we’ve made.”
Even proponents of changing the guideline say that any switch to loose detachment must be done 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 is advisable to extrapolate our data to that environment,” said Dr. Perkins.
Additionally, officials risk confusing the public health news by setting different standards for schools than other common spaces. “I’ve developed further,” said Dr. Linas. “Last summer I felt like, ‘How are we going to explain to people that it’s six feet everywhere except 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 benefits of school are different from the benefits of cinemas or restaurants,” he said. “So I’d be willing to take a little more risk just to keep it open.”