Effectiveness of Contact Tracing for Viral Disease Mitigation and Suppression: Evidence-Based Review

Abstract

Background Contact tracing in association with quarantine and isolation is an important public health tool to control outbreaks of infectious diseases. This strategy has been widely implemented during the current COVID-19 pandemic. The effectiveness of this nonpharmaceutical intervention is largely dependent on social interactions within the population and its combination with other interventions. Given the high transmissibility of SARS-CoV-2, short serial intervals, and asymptomatic transmission patterns, the effectiveness of contact tracing for this novel viral agent is largely unknown. Objective This study aims to identify and synthesize evidence regarding the effectiveness of contact tracing on infectious viral disease outcomes based on prior scientific literature. Methods An evidence-based review was conducted to identify studies from the PubMed database, including preprint medRxiv server content, related to the effectiveness of contact tracing in viral outbreaks. The search dates were from database inception to July 24, 2020. Outcomes of interest included measures of incidence, transmission, hospitalization, and mortality. Results Out of 159 unique records retrieved, 45 (28.3%) records were reviewed at the full-text level, and 24 (15.1%) records met all inclusion criteria. The studies included utilized mathematical modeling (n=14), observational (n=8), and systematic review (n=2) approaches. Only 2 studies considered digital contact tracing. Contact tracing was mostly evaluated in combination with other nonpharmaceutical interventions and/or pharmaceutical interventions. Although some degree of effectiveness in decreasing viral disease incidence, transmission, and resulting hospitalizations and mortality was observed, these results were highly dependent on epidemic severity (R0 value), number of contacts traced (including presymptomatic and asymptomatic cases), timeliness, duration, and compliance with combined interventions (eg, isolation, quarantine, and treatment). Contact tracing effectiveness was particularly limited by logistical challenges associated with increased outbreak size and speed of infection spread. Conclusions Timely deployment of contact tracing strategically layered with other nonpharmaceutical interventions could be an effective public health tool for mitigating and suppressing infectious outbreaks by decreasing viral disease incidence, transmission, and resulting hospitalizations and mortality.

Pattern of COVID 19 Infection among Front line Health Workers and Contact Tracing Done among them. Our Experience in a Tertiary Care Hospital

“…These findings align with findings of our study in shedding light on the importance of contact tracing in prevention and breaking chain of transmission of COVID-19 and also points at few challenges that was faced during contact tracing. 10…”

Cross-sectional survey of compliance behaviour, knowledge and attitudes among cases and close contacts during COVID-19 pandemic

“…Today, many countries have the legal authority to impose quarantine which, in accordance with Article 3 of the International Health Regulations (2005), must be fully respectful of the dignity, human rights and fundamental freedoms of persons [ 15 ]. While contact tracing and quarantine are considered critical activities to reduce transmission [ 2 , 16 ], the effectiveness of contact tracing depends on many factors including compliance [ 17 , 18 ]. A rapid evidence review conducted early in the COVID 19 pandemic identified fourteen studies which assessed compliance to quarantine during earlier infectious disease outbreaks including mumps, Severe Acute Respiratory Syndrome (SARS) and Ebola.…”

COVID-19 Contact Tracing as an Indicator for Evaluating a Pandemic Situation: Simulation Study

“…When systematically applied, contact tracing leads to the breaking of transmission chains, and its valuable role in controlling COVID-19 transmission is widely recognized in the context of low transmission and active community transmission [ 2 ]. It is also acknowledged that the earlier the identification of infection cases and individuals to trace, the higher the likelihood of the pandemic situation being controlled even in instances where contact identification is incomplete [ 1 , 3 , 4 ].…”