A hospital-related outbreak of SARS-CoV-2 associated with variant Epsilon (B.1.429) in Taiwan: transmission potential and outbreak containment under intensified contact tracing, January–February 2021. (September 2021)

• Record Type: Journal Article
• Authors: Akhmetzhanov, Andrei R.; Jung, Sung-mok; Cheng, Hao-Yuan; Thompson, Robin N.
• Is Part Of: International journal of infectious diseases. Volume 110(2021)
• Page Start: 15
• Page End: 20
• Publication Date: 2021-09
• Subjects: COVID-19 -- SARS-CoV-2 -- Epidemic modelling -- End-of-outbreak declaration; Communicable diseases -- Periodicals; Communicable Diseases -- Periodicals; Communicable diseases; Periodicals; Electronic journals; 616.9
• DOI: 10.1016/j.ijid.2021.06.028
• Languages: English
• ISSNs: 1201-9712

Abstract

Highlights: This SARS-CoV-2 outbreak was contained by extensive contact tracing and proactive isolation. Rigorous measures enabled the end of the outbreak to be declared quickly. Less stringent control would have meant lower confidence that the outbreak was over. Public vigilance was still required for several weeks after the final case. Later identification of the outbreak could have led to more infections. ABSTRACT: Objectives: A hospital-related cluster of 22 cases of coronavirus disease 2019 (COVID-19) occurred in Taiwan in January–February 2021. Rigorous control measures were introduced and could only be relaxed once the outbreak was declared over. Each day after the apparent outbreak end, we estimated the risk of future cases occurring in order to inform decision-making. Methods: Probabilistic transmission networks were reconstructed, and transmission parameters (the reproduction number R and overdispersion parameter k ) were estimated. The reporting delay during the outbreak was estimated (Scenario 1). In addition, a counterfactual scenario with less effective interventions characterized by a longer reporting delay was considered (Scenario 2). Each day, the risk of future cases was estimated under both scenarios. Results: The values of R and k were estimated to be 1.30 ((95% credible interval (CI) 0.57–3.80) and 0.38 (95% CI 0.12–1.20), respectively. The mean reporting delays considered were 2.5 days (Scenario 1) and 7.8 days (Scenario 2). Following the final case, ttthe inferred probability of future cases occurring declined more quickly in Scenario 1 than Scenario 2. Conclusions: Rigorous control measures allowed the outbreak to be declared over quickly following outbreak containment. This highlights the need for effective interventions, not only to reduce cases during outbreaks but also to allow outbreaks to be declared over with confidence.