Contact tracing strategies for infectious diseases: A systematic literature review

Contact tracing has been a crucial public health strategy for breaking infectious diseases chains of transmission. Although many resources exist for disease outbreak management none address the rationale of contact tracing. This comprehensive review aims to evaluate contact tracing strategies, their effectiveness, and health systems governance across various diseases to inform a disease-agnostic contact tracing guideline. This systematic review was registered with PROSPERO (ID: CRD42023474507) and follows Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Descriptive and interventional studies in the six official United Nations languages were included, excluding modelling studies and animal-to-human transmission. An electronic search was conducted in Embase, Medline, Medline-in-process, and Cochrane libraries from inception to September 2023. The revised Cochrane Risk of Bias Tool and the Risk of Bias in Non-Randomized Studies of Interventions were used for bias assessment. The search yielded 378 studies, primarily from Europe (29.6%) and North America (21.6%) and focusing on diseases such as the coronavirus disease (COVID-19) (47.4%) or tuberculosis (26.7%). 244 (64.5%) studies addressed contact tracing definitions, commonly based on physical proximity, including duration of contact and sexual partnerships (47.6%) and household exposure (27%). Effectiveness was examined in 330 (87.3%) studies, showing variation across diseases and contexts, with only five studies evaluating epidemiological impacts. Socio-cultural aspects were covered in 166 (43.9%) studies, revealing that stigma and public trust may affect the adherence to contact tracing. Health systems governance was discussed in 278 (73.5%) studies, emphasising the need for coordination among international organisations, national governments, and local health authorities, alongside a sustained and adequately supported workforce. This review provides critical insights into optimising contact tracing strategies. Effective contact tracing requires robust health systems governance, adequate resources, and community involvement. Future research should focus on establishing standardised metrics for comparative analysis and investigating the impact of contact tracing on disease incidence and mortality.