Contact tracing with digital assistance in Taiwan's COVID-19 outbreak response

Abstract

Aim: Comprehensive case investigation and contact tracing are crucial to prevent community spread of COVID-19. We demonstrated a utility of using traditional contact tracing measures supplemented with symptom tracking and contact management system to assist public health workers with high efficiency.

Methods: A centralized contact tracing system was developed to support data linkage, cross-jurisdictional coordination, and follow-up of contacts' health status. We illustrated the process of how digital tools support contact tracing and management of COVID-19 cases and measured the timeliness from case detection to contact monitoring to evaluate system performance.

Results: Among the 8051 close contacts of the 487 confirmed cases (16.5 close contacts/case, 95% CI [13.9-19.1]), the median elapsed time from last exposure to quarantine was three days (IQR 1-5). By implementing the approach of self-reporting using automatic text-messages and web-app, the percentage of health status updates from self-reporting increased from 22.5% to 61.5%. The high proportion of secondary cases detected via contact tracing (88%) might reduce the R0 to under one and minimize the impact of local transmission in the community.

Conclusion: Comprehensive contact tracing and management with complementary technology would still be a pillar of strategies for containing outbreaks during de-escalation or early in the next wave of COVID-19 pandemic.

Keywords: COVID-19; Contact tracing; Coronavirus; Digital tool; Outbreak response.

Figure 1

Distribution of 457 COVID-19 cases and 8,051 close contacts by the time of symptom onset for cases and the time of last exposure for close contacts, Taiwan, January 11–August 26, 2020. The figure does not display 30 asymptomatic confirmed cases.

Figure 2

Timeline from symptom onset to contact follow-up and the information flow during COVID-19 contact tracing in Taiwan. (A) The median time and IQR (interquartile range) between steps from last day of exposure to contact quarantine and the start of health status reporting. The dashed line represents that the timeline between the last day of exposure and the day of contact identification was made retrospectively. (B) Information flow from case confirmation to contact health status monitoring during contact tracing activities. Arrows with a dashed line represent information flow via emails/text messages/calls. NIA: National Immigration Agency; NNDSS: National Notifiable Disease Surveillance System; TRACE: Infectious disease contact tracing platform and management system.