マスクなし会食、感染リスク４倍　大人数・長時間「まだ避けて」―感染研

　会食の席に着くなりマスクを外した人が新型コロナウイルスに感染するリスクは、食べ物を口に運ぶ時以外着用を怠らなかった人の４倍―。そんな調査結果を国立感染症研究所がまとめた。
　緊急事態宣言解除で行動制限が緩和され、会食の機会が増えると心配なのが感染の再拡大。鈴木基感染症疫学センター長は「リスクが高い行動は避け、家族や少人数での飲食にとどめて」としている。
　東京都内５カ所の発熱外来を６～７月に受診した成人７５３人を対象に、発症前２週間の行動について尋ねた。全員がコロナワクチンを１度も接種しておらず、うち２５７人（３４．１％）がＰＣＲ検査で陽性だった。
　会食を全くしなかった人の感染リスクを１として比較した結果、飲食物を口に入れる時以外マスク着用を続けた人のリスクは０．９８倍でほぼ同じだった。一方、着席直後に取るか着けずに飲食した人は３．９２倍に跳ね上がった。料理が運ばれた時点で外してもリスクは高まった。
　飲食店での滞在が２時間以上に及ぶと、リスクは１．８７倍となった。酒がない席への参加ならリスクはさほど高くないが、飲酒した場合は２．１８倍に上がった。参加人数でみると、５人以上での会食は、５人未満に比べリスクが１．５倍に。一方、外食でも１人なら問題はなかった。
　感染研の脇田隆字所長は、会食時は「少人数、２時間以内、マスク着用」で感染リスクを減らすよう求めている。（2021/10/09-22:09）

The risk of novel coronavirus infection for people who remove their face masks as soon as they take seats for dining with others is four times that for those who keep their masks on except when eating or drinking, a Japanese survey has found.
   The survey was conducted by the National Institute of Infectious Diseases amid mounting concerns that new infection cases could surge again if an increasing number of people dine with friends or others after the government lifted its COVID-19 state of emergency at the end of last month.
   Motoi Suzuki, who heads the NIID's Infectious Disease Surveillance Center, called on people to "avoid high-risk activities, and only eat and drink with family members or in a small group."
   The survey covered a total of 753 adults who visited five medical institutions with facilities for outpatients with fever in Tokyo between June and July. They were asked about their records of activity in the two weeks before exhibiting their symptoms. None of the patients had received COVID-19 vaccines, and 257 of them, or 34.1 pct, tested positive for the virus.
   The infection risk for those who kept their masks on except when eating or drinking during dining with other people was almost the same as that for those who had no such opportunities, according to the survey. But the risk was 3.92 times higher for people who removed their face masks as soon as they were seated or did not wear masks during dining events.