Using an app for COVID-19 contact tracing costs less per person traced than manual tracing: microcosting analysis of a randomised trial in Cameroon - Boris Tchounga; Rigveda Kadam; Godfrey Woelk; Rhoderick Machekano; Anne-Cecile Zoung-Kanyi Bissek; Appolinaire Tiam; Patrice Tchendjou; Leonie Simo; Tatiana Djikeussi; Laura Guay; Olukunle Akinwusi; Khairunisa Suleiman; et al. (BMJ Public Health)