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Three feet, not six: A new norm for physical distancing

Physical distancing guidelines must be updated to reflect new science

CHICAGO --- Physical distancing with masks for the general public should shrink to 3 feet from the current recommendation of 6 feet, says Dr. Robert Murphy, executive director of the Institute for Global Health at Northwestern University Feinberg School of Medicine. 

Murphy’s recommendation follows the new updated guidelines today from Centers for Disease Control, which recommended K-12 schools should separate students wearing masks at least 3 feet. 

“There’s no reason we can’t expand this to outside of the schools,” said Murphy, a professor of infectious diseases at Feinberg. “We must keep the masks, though. That is crucial.”

The 3-foot mark is the critical distance at which secretion droplets — which travel in an arc — have already begun their descent to the ground and fallen below the nose and mouth of a passerby. Droplets are the preliminary way COVID-19 is spread from person to person.

“This will have a huge effect,” Murphy said. “Trying to keep 6 feet away from people – that is a 12-foot diameter circle. We don’t have enough room for that. That’s a very large circle required to isolate yourself. If that circle was only 6 feet with you in the middle, it would make things a lot easier.”

Murphy stressed this 3-foot distance doesn’t apply to a gym or health club, a choir or contact sports. “This is only for everyday living in a lower risk environment,” he said.

To interview Dr. Murphy, contact marla-paul@northwestern.edu.

The evidence for the 3 feet of social distancing is based on a study soon to be published in Clinical Infectious Diseases: “Effectiveness of three versus six feet of physical distancing for controlling the spread of COVID-19 among primary and secondary students and staff:  a retrospective, state-wide cohort study” and a study in The Lancet: “Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19:  a systematic review and meta-analysis, June, 2020.”