Relaxation of face mask requirements in restaurants, coffee shops and bars could make those venues prime areas for transmission of the new coronavirus, research shows.
The new study compared the behaviors of people diagnosed with COVID-19 and those without such diagnoses.
It uncovered one clear difference: Newly ill people without any known contact with a person with COVID-19 were almost three times as likely to have patronized a restaurant over the prior two weeks, and almost four times as likely to have visited a bar or coffee shop, compared to uninfected people.
The study suggests that situations "where mask use and social distancing are difficult to maintain, including going to places that offer on-site eating or drinking, might be important risk factors for acquiring COVID-19," the research team said.
The findings come at a moment when more locales are allowing eating establishments and bars to reopen. Just this week, officials announced that restaurants in New York City could serve customers again starting Sept. 30, albeit with a 25% occupancy limit.
"As we learn more about transmission, it is not surprising that activities that cannot maintain social distancing and are not amenable to mask wearing -- such as eating and drinking in close proximity to others -- would result in a higher transmission rate," said Dr. Teresa Murray Amato, who heads emergency medicine at Long Island Jewish Forest Hills, a hospital in New York City.
She wasn't involved in the new study, which was led by Kiva Fisher of the U.S. Centers for Disease Control and Prevention's COVID-19 Response Team. Fisher and her colleagues conducted detailed interviews with 314 U.S. adults during the month of July, about half of whom were diagnosed with COVID-19.
Comparing the activities of people who did and did not have COVID-19, the investigators found no significant differences in their patronage of venues where the use of face masks at all times was required -- activities such as taking public transportation, shopping or attending church.
Mask use was common among most of the study participants. A similar number of people with or without COVID-19 said they always wore some kind of mask or face covering when out in public -- 71% and 74%, respectively.
The only big difference in terms of behavior between the infected and uninfected groups was a visit over the prior two weeks to a bar, restaurant or coffee shop, Fisher's group found.
More than half -- 58% -- of study participants diagnosed with COVID-19 said that they'd had no close contact with a person known to have been infected with the new coronavirus. But these individuals did have 2.8 times the odds of having patronized a restaurant over the prior two weeks, and 3.9 times the odds of having been at a bar or coffee shop, compared to uninfected people.
The study wasn't able to ascertain whether participants had consumed food or drinks in an indoor or outdoor space.
"The bottom line is that many people don't put their mask back on when they aren't eating and drinking, and may be engaged in conversation," said Dr. Robert Glatter, an emergency medicine physician at Lenox Hill Hospital in New York City. "This very fact increases the risk of transmission, and is compounded by lack of enforcement by management at eating and drinking establishments."
Glatter also noted that ventilation within restaurants or bars is often less than adequate, and research has shown that "aerosolized droplets containing virus in normal conversation may be transmitted to others in close proximity, but may also remain suspended in air for up to 3 hours and travel as far as 13 feet during normal conversation. Such aerosolized droplets may also travel as far as 26 feet during sneezes and 15 feet during coughs."
Finally, he said, alcohol is often a factor. Drinking "makes people move closer together, speak louder," Glatter said, "thereby generating more aerosolized droplets that may contain infectious viral particles."
The study is published in the Sept. 11 issue of the CDC's Morbidity and Mortality Weekly Report.
The U.S. Centers for Disease Control and Prevention has more on the new coronavirus.
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