A Just-In-Time Unmanned Aerial Vehicle (UAV) Vaccine Supply Reduces Cold-Chain Storage in Rural Rwanda: A Prospective Interventional Study

Background: The vaccine cold-chain (VCC) is critical national infrastructure that has contributed to a 52% reduction in infant mortality in the WHO Africa region over the 50-years since the initiation of the WHO Expanded Programme of Immunisation. However, fragile public health infrastructure in sub-Saharan African settings results in widespread immunity gaps and a subsequent high burden of avoidable morbidity and mortality across the continent.

Methods: This was a prospective, multicentre, supply logistics interventional study conducted over a six-month period in 16 rural health centres in Eastern Rwanda. The study was designed to evaluate a just-in-time model of vaccine supply using unmanned aerial vehicle (UAVs, or drones) to minimise the quantities of vaccines requiring storage at rural African vaccination clinics.

Findings: UAV delivery was fast, frequent and responsive to the needs of clinical care provision. Once fully dependent on the just-in-time vaccine supply by UAV, vaccine storage at health centre level was an average of 99 doses (average 24 vaccine vials), compared to 5,858 doses (average 889 vaccine vials) for road-supplied control health centres. Expressed as a relative area-under-the-curve (AUC), vaccine storage requirements were 95-98% lower by use of a just-in-time UAV supply model. There was no detrimental impact on the provision of clinical services or vaccine wastage.

Interpretation: The just-in-time UAV vaccine supply model can reduce the risks associated with vaccine storage in remote, rural African settings.