Association of public health interventions and COVID-19 incidence in Vietnam, January to December 2020

Background: Vietnam implemented various public health interventions such as contact tracing and testing, mandatory quarantine, and lockdowns in response to coronavirus disease 2019 (COVID-19). However, the effects of these measures on the epidemic remain unclear. Methods: This article describes the public health interventions in relation to COVID-19 incidence. Maximum likelihood estimations were used to assess containment delays (time between symptom onset and start of isolation) and multivariable regression was employed to identify associated factors between interventions and COVID-19 incidence. The effective reproductive numbers (Rt) were calculated based on transmission pairs. Results: Interventions were introduced periodically in response to the epidemic. Overall, 817 (55.4%) among 1474 COVID-19 cases were imported. Based on a serial interval of 8.72 +/- 5.65 days, it was estimated that Rt decreased to below 1 (lowest at 0.02, 95% CI 0-0.12) during periods of strict border control and contact tracing, and increased ahead of new clusters. The main method to detect cases shifted over time from passive notification to active case-finding at immigration or in lockdown areas, with containment delays showing significant differences between modes of case detection. Conclusions: A combination of early, strict, and consistently implemented interventions is crucial to control COVID-19. Low-middle income countries with limited capacity can contain COVID-19 successfully using non-pharmaceutical interventions. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

Automated summary

The study found that early, strict, and consistently implemented public health interventions were crucial in controlling the COVID-19 epidemic in Vietnam. The effective reproductive number (Rt) decreased to below 1 during periods of strict border control and contact tracing, but increased ahead of new clusters.