Selected Articles

Of the 2,052 articles initially found, 797 were duplicates, 1,247 were screened by title and abstract and excluded, eight were retrieved (and fully read) of which five met the eligibility criteria and were included in the review. Figure 1 (PRISMA 2020 flow diagram for new systematic reviews) summarizes the identification, screening, and inclusion of articles [20]. Table 2 presents the characteristics of the selected studies, including author, year, country, sample sort, UAV model, comparator, and UAV operation.

Fig. 1

PRISMA 2020 flow diagram for new systematic reviews which included searches of databases, registers and other sources.20

Reference: Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021; https://doi.org/10.1136/bmj.n71

Table 2 Summary of selected studies’ characteristics (author, year, country, sample sort, UAV model, comparator, and UAV operation)UAV Payload Capacity and Safety

Among studies that reported UAV payload specifications, weight capacity ranged from 3 to 45 kg [1, 2, 21], and the volume from 1,200 to 5,362.5 cm3 [1, 21]. The number of samples transported per UAV flight varied from 4 to 50 per route [1, 2, 8, 22].

Reported flight safety concerns included unsafe routes, weather conditions and UAV loss of C2 link (“Command and Control” link, which is the communication pathway between the UAV and its ground control station) which can lead to crashes [2, 8, 21, 22].

Suggested solutions comprised defining safe routes [2, 21], adhering to weather conditions protocols [2, 8, 21, 22], using UAV safety devices (e.g., parachutes) and appropriate containers [1, 2, 8, 21], and complying with national Aviation Regulations for UAV transport [2, 21]. One article emphasized the need to develop a C2 link based on a redundant navigation system (e.g., radio frequency and cellular network) [21], and other cited the importance of community awareness campaign prior to the drone flights, ensuring that the population is informed about the purpose, procedures, and protocols for potential adverse events [1].

About the success of UAV flights, García et al. reported that 10 out of 16 flights happened without unexpected events (success rate of 62.5%) [21]. Thakur et al. successfully completed 151 of 180 planned UAV flights (83.8%). Other studies did not report losses. Mentioned causes of UAV operations failures encompassed low flight altitude, coordinate air traffic control (ATC) failure, unsynchronized ground control station, loss of C2 link, balloon trajectory flight, and weather conditions [21, 22].

Table 3 summarizes the characteristics of the UAV used in the included studies, focusing on payload capacity and safety of the flights.

Table 3 Summary of UAV payload capacity and flights safetySamples Conservation

To ensure sample conservation, the studies adhered to standard collection and packaging protocols, including triple packaging in accordance with IATA (International Air Transport Association) and WHO (World Health Organization) guidelines, as well as the use of ice packs and temperature monitoring sensors [1, 2, 8]. Encoding sample identification (e.g., barcoded) was a strategy used to maintain patient confidentiality and sending case investigation forms [1, 8].

Two studies reported temperature monitoring of cargo box (or container) during the flights. In the first, it ranged from 3 °C to 8 °C during air transportation, while control samples ranged from 2 °C to 6 °C during ground transportation [1]. In the second, the UAV container carried individually compartmentalized supplies with refrigeration maintained at 4 °C [2].

Distance Travelled, time Saved and Flight Parameters

Analysis of UAV flight distances was limited, as the included studies reported only land travel distances rather than precise aerial route measurements.

Sylverken et al., in Ghana, reported that the average travel time by road from the Zipline office to the Kumasi Centre for Collaborative Research (KCCR) was 96 min over a distance of approximately 63 km. The same route covered by an UAV took an average of 39 min, with a range of 36.5 to 43.3 min. However, the study did not provide a precise measurement of the actual distance traveled by the UAV between the Zipline office and KCCR [8].

Thakur et al., in India, found that UAVs reduced delivery time by approximately threefold, with an average duration of 7.1 ± 0.8 min compared to 22.7 ± 4.6 min by motorbike. The study reported a clear difference in the mean distances traveled: 12.09 ± 1.6 km by motorbike versus 2.89 ± 0.35 km by UAV [22].

The longest time of flight registered was 42 min [2]; flight altitude ranged from 40 to 90 m [2, 21]; and the average flight speed reported from 10 to 93 km/h [1, 2] (Table 4).

Table 4 UAV flights comparable parameters: maximum distance travelled per charge, altitude, time of flight and average speedCost and Effectiveness

Flemmons et al., in Canada, provided a broader overview of UAV acquisition costs, highlighting significant cost variability, depending on the expected resistance of the UAV model: medium resistance ones range between US$ 7,000 and US$ 15,000, while high resistance ones can cost from US$ 200,000 to US$ 600,000 [2].

Thakur et al. assessed per route costs and concluded that each UAV trip (US$ 0.30) was more than four times cheaper than the motorcycle route (US$ 1.30) [22].

Quality Assessment of Transported Samples

Two studies evaluated the quality of the biological respiratory samples transported by UAV. One of them did not identify any changes compared to land transport, founding fungal contamination in TB respiratory samples in solid culture at a rate of 3% (five samples) for UAV and 1% (two samples) for land transport, with no contamination in the liquid culture [1]. The other, which tested the reliability of the COVID-19 test and spiked viral transport media or saline used in COVID-19 or other respiratory virus sampling kits under varying temperatures and higher altitudes, considering the conditions at the simulation site, did not get sufficient data to validate the proof-of-concept, and recommended further research to access how extreme environmental and weather conditions may affect the flights performance and specimen integrity [2].

Regulatory and Legal Landscape

The regulatory and legal landscape were cited by Flemons et al. as one of the primary challenges in establishing drone-based delivery for healthcare and other purposes in Canada. In this context, developing tested and approved Standard Operating Procedure (SOP) and safety documents was defined as a critical prerequisite for enabling sector-wide innovation and impact [2].

García et al., in Spain, highlighted that, under European Union (EU) regulatory framework, delivery operations required extended range fall under specific regulations due to their interest in operating beyond visual line of sight (BVLOS) and extended visual line of sight (EVLOS). BVLOS operations rely on detect and avoid (DAA) systems to ensure collision prevention. Approval for BVLOS operations also requires a Specific Operations Risk Assessment (SORA) and authorization. To obtain authorization for the operations by AESA (Spanish Safety Aviation Agency), it was necessary to assess risk performing a SORA for each of the three scenarios tested. Moreover, for “dangerous goods” like medical items (e.g., pathogen samples or untested blood), additional safety measures, such as the use of secure container, are mandated to prevent risks during transport [21].

Flemons et al. worked with Transport Canada to obtain approval for BVLOS operations based on the robust standard operating procedures, safety and emergency procedures, besides developing detect and avoid (DAA) systems by the project. In terms of safety documentation, SOPs for each UAV, payload system, and flight operation tested (VLOS, EVLOS and BVLOS), were enhanced to include checklists aligned with the Canadian Aviation Regulations (i.e., site survey, preflight, and postflight), and mission mapping and safety details [2].

With regard to transporting infectious substances (i.e., diagnostic samples), transportation requirements (governed by Transport Canada and the United Nations – UN – designations for the transport of dangerous goods) will need to be updated and amended to include drones [2].