Epidemiology of Hospital-Based COVID-19 Cluster in Hospital A, Chennai, India

Objectives: To identify risk factors associated with COVID-19 in a hospital-based cluster and to recommend control measures. Methods: We conducted contact-tracing and testing in the hospital and community. We collected information through telephone interviews, abstraction of patient’s clinical records and registers. We described the cluster by time, place and person. We conducted an unmatched case-control study. We computed Odds Ratio (OR) with 95% confidence interval(CI) by comparing attack rates among those exposed and unexposed to the risk factors. Results: The secondary attack rate of COVID-19 was high among in-patients of block A, household contacts and housekeeping staff. The cluster started on 22nd April, had 2 peaks on 26th April and 1st may and lasted till 8th May. Males, older patients (OR-30·7, 95% CI;3·6-264), hypertensives (OR-4·3,95% CI;1·1-16·7) and diabetics (OR-3·8, 95%CI;1·0-14·1) were more likely to be COVID-19 positive. Mask compliance was poor (20%) among hospital workers. Discussion: We suggest screening of all patients for diabetes and hypertension and isolation/testing of anyone with influenza-like illness. Strict adherence to infection control practices will prevent such clusters in hospital settings. Funding Statement: Indian Council of Medical Research. Declaration of Interests: None to declare. Ethics Approval Statement: The study protocol was approved by the institutional human ethics committee of Hospital A. Informed consent was obtained from the participants before commencing the telephone interview.