Uncrewed aircraft systems versus motorcycles to deliver laboratory samples in west Africa: a comparative economic study

Abstract

Background: Transportation of laboratory samples in low-income and middle-income countries is often constrained by poor road conditions, difficult geographical terrain, and insecurity. These constraints can lead to long turnaround times for laboratory diagnostic tests and hamper epidemic control or patient treatment efforts. Although uncrewed aircraft systems (UAS)-ie, drones-can mitigate some of these transportation constraints, their cost-effectiveness compared with land-based transportation systems is unclear.

Methods: We did a comparative economic study of the costs and cost-effectiveness of UAS versus motorcycles in Liberia (west Africa) for transportation of laboratory samples under simulated routine conditions and public health emergency conditions (based on the 2013-16 west African Ebola virus disease epidemic). We modelled three UAS with operational ranges of 30 km, 65 km, and 100 km (UAS30, UAS65, and UAS100) and lifespans of 1000 to 10 000 h, and compared the costs and number of samples transported with an established motorcycle transportation programme (most commonly used by the Liberian Ministry of Health and the charity Riders for Health). Data for UAS were obtained from Skyfire (a UAS consultancy), Vayu (a UAS manufacturer), and Sandia National Laboratories (a private company with UAS research experience). Motorcycle operational data were obtained from Riders for Health. In our model, we included costs for personnel, equipment, maintenance, and training, and did univariate and probabilistic sensitivity analyses for UAS lifespans, range, and accident or failures.

Findings: Under the routine scenario, the per sample transport costs were US$0·65 (95% CI 0·01-2·85) and $0·82 (0·56-5·05) for motorcycles and UAS65, respectively. Per-sample transport costs under the emergency scenario were $24·06 (95% CI 21·14-28·20) for motorcycles, $27·42 (95% CI 19·25-136·75) for an unadjusted UAS model with insufficient geographical coverage, and $34·09 (95% CI 26·70-127·40) for an adjusted UAS model with complementary motorcycles. Motorcycles were more cost-effective than short-range UAS (ie, UAS30). However, with increasing range and operational lifespans, UAS became increasingly more cost-effective.

Interpretation: Given the current level of technology, purchase prices, equipment lifespans, and operational flying ranges, UAS are not a viable option for routine transport of laboratory samples in west Africa. Field studies are required to generate evidence about UAS lifespan, failure rates, and performance under different weather conditions and payloads.

Funding: None.

Figure 1:. Road networks and distribution of clinics in Liberia

Black squares indicate the county hospitals where the reference laboratories were located. Black dots indicate clinics.

Figure 2:. Emergency transport simulations

Figure shows emergency transport simulations for Ebola virus disease in the aircraft operational collection ranges of 65 km (uncrewed aircraft systems [UAS] 65), 30 km (UAS30), and 100 km (UAS100). Black dots represent peripheral clinics. Red dots indicate an Ebola virus disease laboratory site. Blue circular areas represent the operational radius using the reference laboratory as the origin.

Figure 3:. Routine transport

Figure shows geographical coverage under routine programming in the aircraft operational collection ranges of 65 km (uncrewed aircraft systems [UAS] 65), 30 km (UAS30), and 100 km (UAS100). Black dots represent peripheral clinics. Red dots indicate a county referral hospital. Blue circular areas represent the operational radius.

Figure 4:. Cost-effectiveness plane (A) and per-sample costs over lifespan (B) under routine scenario

Values shown for the aircraft operational collection ranges of 30 km (UAS30), 65 km (UAS65), 100 km (UAS100), and for motorbikes. Scenario based on a UAS lifespan of 3000 h and cost of US$10 000. Error bars show 95% CIs based on 10 000 simulations. Shaded area represents plausible lifespan. UAS=uncrewed aircraft systems.

Figure 5:. Cost-effectiveness plane (A) and per-sample costs over lifespan (B) under emergency scenario

Values shown for the aircraft operational collection ranges of 30 km (UAS30), 65 km (UAS65), 100 km (UAS100), and motorbikes. Scenario based on a UAS lifespan of 3000 h and cost of US$10 000. Error bars show 95% CIs based on 10 000 simulations. Shaded area represents plausible lifespan. Additional motorbikes required in short-range UAS scenario. UAS=uncrewed aircraft systems.