Effectiveness of contact tracing to reduce fatality from COVID-19: preliminary evidence from Colombia

Fernández-Niño, Julián Alfredo; Peña-Maldonado. Economist, Carlos; Rojas-Botero, Maylen; Rodríguez-Villamizar, Laura Andrea

Objectives Conducting contact tracing programs in low and middle-income countries is challenging and there is no evidence of their effectiveness in Latin America. We evaluated the effectiveness of contact tracing on reducing fatality from COVID-19 in Colombia. Study design Retrospective cohort study with nation-wide data of suspected and confirmed cases of SARS-CoV-2 infection and their registered contacts. Methods We analyzed confirmed and suspected COVID-19 cases and their chains of contact using a nation-wide registry from March 28, 2020 to January 13, 2021. To estimate the effect of contact tracing on fatality we adjusted a multilevel negative binomial model using as outcome variable the number of deaths and off-set variable the number of people within a chain of contacts. Sensitivity analysis was conducted using different cut-off values of contacts traced and a logistic model for the effect of contact tracing on death at individual level. Results We analyzed 1,4 million cases, 542 936 chains of contact, and 46 087 deaths. Only 5,8% of total cases and contacts were included in a chain of a case and five or more contacts. We found that tracing of at least five contacts per case reduce fatality by 48% (95% CI: 45-51) and, at the current levels of tracing in Colombia, it prevents 1.8% of deaths. Results obtained from the sensitivity analysis were consistent with the reduction of fatality at individual level and higher protective effect with higher number of contacts traced. Conclusions In Colombia, tracing of at least five contacts per case reduces fatality from COVID-19. The coverage and intensity of tracing needs to be increased as a strategy to mitigate fatality in Colombia.