Abstract
INTRODUCTION: SARS-CoV-2 contact tracing in Cameroon has been done manually using paper forms and phone calls. However, there were reports of inaccurate contact details, resulting in delays in identifying and testing contacts. A recently introduced digital contact-tracing module using the Mamal Pro app automatically sends SMS messages to notify all reported contacts and the district unit. We assessed the total costs, cost per contact reached, tested and found SARS-CoV-2-positive for both manual (standard of care, SOC) and app-based (intervention, ITV) contact-tracing approaches. METHODS: A cluster randomised trial comparing the SOC and ITV was implemented across eight health districts in Cameroon between October 2022 and March 2023. The cost per contact reached, tested and found SARS-CoV-2-positive was calculated by dividing the total cost of each approach by the number of contacts reached, tested and found SARS-CoV-2-positive, respectively. We also estimated the minimum number of SARS-CoV-2-positive contacts that need to be found and the maximum total cost of ITV in order to equal the SOC's cost per SARS-CoV-2-positive contact. RESULTS: In the SOC, of 849 contacts identified, 463, 123 and 5 were reached, tested and found SARS-CoV-2-positive, respectively. In the ITV, of the 854 contacts identified, 801, 182 and 4 were reached, tested and found SARS-CoV-2-positive, respectively. In the SOC, the cost per contact reached was US$70, per contact tested was US$262 and per SARS-CoV-2-positive contact was US$6437. In the ITV, the cost per contact reached was US$48, per contact tested was US$210 and per SARS-CoV-2-positive contact was US$9573. The minimum number of SARS-CoV-2-positive contacts the ITV needs to find and the maximum total cost of the ITV to equal the SOC's cost per SARS-CoV-2-positive were 6 and US$25 748, respectively. CONCLUSION: Using the Mamal Pro digital contact tracing app module increased the number of clients' contacts reached and tested for SARS-CoV-2 and reduced the cost per contact reached and tested. TRIAL REGISTRATION NUMBER: NCT05684887.