A group of researchers has found the risk of coronavirus infection increases nearly four-fold when people eat or drink with companions without wearing masks at all during the gathering, compared to when people avoid group meals altogether.
The researchers, who include experts with the National Institute of Infectious Diseases, surveyed 753 unvaccinated adults who sought medical attention in Tokyo for fever or other symptoms. Of the subjects, 257 tested positive for COVID-19 while 496 were negative.
The researchers found people who had gone out to eat or drink in groups and not used a mask at any time had tested positive at a rate 3.92 times that of people who had not dined in groups at all before developing symptoms.
The risk of infection for people who went out in groups and mostly kept their masks on, removing them occasionally to eat or drink, wasn't very different than for people who did not dine in groups at all.
The researchers also found that the rate of infection for people who wore urethane masks was 1.87 times that for people who wore non-woven fabric masks, and for those who wore cloth or gauze masks, it was 1.82 times.
The head of the NIID Infectious Disease Surveillance Center, Suzuki Motoi, called on people to wear non-woven fabric masks properly when meeting companions. He also cautioned against eating out in large groups for long periods of time.