2019年12月、中国武漢で、severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)感染によるcoronavirus disease 2019 (COVID-19)の流行が始まり、その後、世界的流行となった。現在、COVID-19は最も深刻な公衆衛生上の問題となっている。
慶應義塾は医学部と大学病院を有しているが、医療機関では、SARS-CoV-2の感染リスク、COVID-19の発症リスクの高い免疫能が低下した患者、高齢の患者の診療が行われており、COVID-19集団発生のリスクが高い。そこで、本学医学部と大学病院の教職員を対象に、SARS-CoV-2に対する血清IgG抗体価を測定し、医療従事者における既感染率を推測、更に、臨床情報から軽症のCOVID-19の臨床的特徴を調査し、COVID-19に対する効果的な感染対策を検討した。
2341人の教職員が研究に参加した。その内、21名がCOVID-19の罹患歴があった。COVID-19の罹患歴がある者を除いた2320人中20名(0.862%)が抗体陽性であった。抗体陽性者では抗体陰性者に比べ、発熱、嗅覚または味覚障害の頻度が高かった(オッズ比 5.475、95%信頼区間 1.960–15.293、オッズ比 24.158、95%信頼区間 2.693–216.720)。一方、適切な感染対策をして、COVID-19患者の診療にあたった医療従事者とその他の医療従事者では、抗体陽性率に差を認めなかった(オッズ比 2.514、95%信頼区間 0.959–6.588)。
医療機関においてCOVID-19集団発生のリスクを軽減するために、医療従事者は標準予防策、感染経路別予防策を取り、発熱、嗅覚または味覚障害を認めた場合は可及的速やかに業務を停止すべきである。
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection caused the outbreak of coronavirus disease 2019 (COVID-19) that first occurred in December 2019 in Wuhan, China, and was subsequently disseminated worldwide. COVID-19 is currently the most serious public health crisis in the world.
Keio University has a medical school and a university hospital. Medical institutions are at high risk for COVID-19 outbreaks because these institutions serve many patients who are immunocompromised as well as older patients, both populations that may be easily susceptible to SARS-CoV-2 infection and develop COVID-19. To consider effective measures against COVID-19 in medical institutions, this study analyzed the results of serologic test to detect immunoglobulin G antibodies against SARS-CoV-2, and estimated the SARS-CoV-2 infection rate among faculty of Keio University School of Medicine and healthcare workers (HCWs) of Keio University Hospital. In addition, this study evaluated the medical information for faculty of Keio University School of Medicine and HCWs of Keio University Hospital, and determined the specific findings for mild COVID-19 cases.
This study recruited 2341 faculty and HCWs, 21 of whom had a COVID-19 history. Of the 2320 participants without a COVID-19 history, 20 (0.862%) had positive serologic test results. Fever and dysgeusia or dysosmia occurred with greater frequency among the participants with positive versus negative test results (Odds ratio (OR), 5.475; 95% confidence interval (CI), 1.960–15.293 and OR, 24.158; 95% CI, 2.693–216.720, respectively). No significant difference was observed in the positivity rate between HCWs providing medical care for COVID-19 patients using adequate protection and the other HCWs (OR, 2.514; 95% CI, 0.959–6.588).
To reduce the risk of COVID-19 spread in medical institutions, faculty and HCWs should follow standard and necessary transmission-based precautions, and those with fever and dysgeusia or dysosmia should excuse themselves from work as soon as possible.