Effectiveness of contact tracing for viral disease mitigation and suppression: Evidence-based review

Kelly Jean Thomas Craig, Rubina Rizvi, Van C. Willis, William J. Kassler, Gretchen Purcell Jackson

Research output: Contribution to journalReview articlepeer-review

17 Scopus citations


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.

Original languageEnglish (US)
Article numbere32468
JournalJMIR Public Health and Surveillance
Issue number10
StatePublished - Oct 2021
Externally publishedYes

Bibliographical note

Funding Information:
The study is supported by IBM Watson Health. No direct funding was received for this study. The funder of the study did not have a role in study design, screening, data extraction, synthesis, evaluation, or writing of the manuscript.

Publisher Copyright:
© 2021 Fundacion Instituto de Historia Social. All rights reserved.


  • COVID-19
  • Contact tracing
  • Effectiveness
  • Epidemic
  • Intervention
  • Isolation
  • Mitigation
  • Monitoring
  • Non-pharmaceutical interventions
  • Outcome
  • Pandemic
  • Protection
  • Review
  • Spread
  • Surveillance
  • Testing
  • Transmission
  • Viral disease


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