Table 1

Main technical assumptions for the cost-effectiveness simulation model

 Mother-to-child transmission rate at 6 weeks7.7%Point estimatePNLSH*
 HIV-exposed infant receiving PCR test at 6 weeks64.4%(47.5–81.2)Random point estimate26
 Mothers' arrival time at the health centre9:00 hours(7:00–16:30 hours)Beta PERTField survey (online supplemental appendix 3)
 Waiting time before being seen in consultation (min)133.8SD: 66.7Normal with truncation of negative valuesLiterature review (online supplemental appendix 4)
 Time required to perform a PCR test at the central laboratory (min)105(90 –120)Random point estimateField observations with GeneXpert
 Work departure time of healthcare workers in postnatal services16:30Point estimateField observations
 Mothers able to wait until healthcare workers leave40.2%(10.6–69.9)Point estimateField survey (online supplemental appendix 5)
 Maximum duration mothers can wait in the health centre (min)160(3 –570)Beta PERTField survey (online supplemental appendix 5)
 No of days needed to return for the test results if not collected the same day (median)21(0–365)Cumulative gammaLiterature review (online supplemental appendix 6)
 Median number of days for collection-to-results turnaround times (baseline scenario)35(0–365)Cumulative gammaLiterature review (online supplemental appendix 7)
 ART initiation acceptance rates92.3%Point estimate4
 Average age at ART initiation among children after 1 year4.7(1.0–21.7)ExponentialIeDEA data (online supplemental appendix 8)
 UAV priceUS$11 562Point estimateDeltaQuad
 Operational horizontal speed (km/hour)65Point estimateDeltaQuad
 Operational vertical speed (km/hour)4.32Point estimateDeltaQuad
 Flight altitude required (metres)80Point estimateField observations
 Autonomy (min)110Point estimateDeltaQuad
 Maximal flight distance (km)100Point estimateDeltaQuad
 Preparation times, for example, UAV deployment (min)4Point estimateDeltaQuad and Field observations
 Weather inoperability2.7%Point estimateMeteoblue (online supplemental appendix 9)
 UAV loss rates (per 100 000 flights)2.5(0.0–5.0)Point estimateDrone Volt, DeltaQuad, assumptions†
 Motorcycle price$3238Point estimateCFAO motors Guinea
 Lifespan (en km)55 000(30 000–70 000)Beta PERT14
 Breakdown rate (per 10 000 km)0.6Point estimate14
 Minor accident rate (per 100 000 km)1.65Point estimate14
 Major accident rate (per 100 000 km)0.43Point estimate14
 Weather inoperability0.2%Point estimateMeteoblue (online supplemental appendix 9)
  • *Routine data collected in Conakry by the National Programme for HIV and hepatitis (Programme National de Lutte contre Le VIH/Sida et les Hepatites) in 2021 among 881 HIV-exposed children tested at 6 weeks in public health centres (68 positive results).

  • †We based our assumptions on publicly available data on the Alphabet’s drone service ( operating on-demand delivery in US, Finland and Australia. To date, 5 crashes have been reported (3 in Australia and 2 in Finland) for a total of 200 000 flights.

  • ART, antiretroviral therapy; CFAO, Corporation For Africa & Overseas; IeDEA, International epidemiology Databases to Evaluate AIDS; PERT, Program evaluation review technique; UAV, unmanned aerial vehicles.