When the COVID-19 global pandemic led to lockdowns and travel restrictions, the U.S. President’s Malaria Initiative (PMI) VectorLink Project adapted its work in the field to continue to protect people from malaria while mitigating the risk of COVID-19. Furthermore, the project modified its monitoring activities, including assessing the efficacy of vector control tools, such as insecticide-treated nets (ITNs).
The PMI VectorLink Project works with National Malaria Control Programs (NMCPs) to assess the durability and estimated average useful life of an ITN. These durability monitoring studies generate data on the survivorship, physical durability, and insecticidal effectiveness of ITNs over the three years following a mass distribution campaign.
However, the COVID-19 pandemic presented serious challenges to implementing durability monitoring since data is gathered using an in-depth household survey, net assessments, cone bioassays, and chemical content testing. The PMI VectorLink Project had to adapt quickly to mitigate the risk of COVID-19 for study participants and field teams so ITN durability monitoring activities could continue in nine countries.
These adaptations included wearing masks and gloves while in the field, frequent use of hand sanitizer, switching from written to oral consent to participate in the study round, limiting the number of individuals in field vehicles, and altering the method of net assessment by measuring holes with a ruler on the outside of the net to minimize contact with it.
Training processes were also altered in response to COVID-19. In all nine countries, PMI VectorLink Project conducted online training-of-trainers (TOT) followed by an in-person field worker training. In total, 162 hours of virtual TOT were conducted with 78 individuals from local data collection agencies, NMCPs, VectorLink, and global partners. Following TOT, local study leads conducted in-person fieldworker trainings to prepare fieldworkers for data collection. In-person activities reinforced COVID-19 mitigation measures, with trainings conducted outdoors where possible, participants maintaining physical distancing guidelines, and masks worn by all participants.
Burundi, Ghana, Liberia, Madagascar, and Niger were all scheduled to conduct data collection before August 2020, but a variety of in-country COVID-19 restrictions prevented activities from being carried out as planned. As soon as country restrictions were lifted, fieldwork continued with only minimal delays. Between September and December 2020, Burkina Faso, Kenya, Rwanda, and Sierra Leone conducted data collection as scheduled. By the end of 2020, PMI VectorLink had effectively and efficiently carried out all planned 2020 activities over five months rather than the originally planned 10 months.
For all nine countries combined, over a period of 140 days, data collectors visited 314 clusters where 126 fieldworkers were involved in administering surveys and assessing cohort mosquito nets. To date, 3,600 households have been visited, data has been collected on 7,600 nets, and more than 3,500 nets have been assessed for holes.
In addition to the household surveys and cohort nets, fieldworkers also collected 630 campaign nets to undergo bioassay analysis. These tests were conducted by seven different partners in Burkina Faso, Burundi, Ghana, Kenya, Liberia, Madagascar, and Niger.
Bioassays were also performed on new types of nets (piperonyl-butoxide [PBO] and Interceptor G2 brand [IG2]) for the first time as a part of the Burkina Faso study. PBO and IG2 nets are likely to play an important role in controlling pyrethroid-resistant malaria vector species and were distributed in Burkina Faso in 2019. Bioassay standard operating procedures (SOPs) for PBO and IG2 brand nets were developed by PMI, and Burkina Faso was the first PMI VectorLink-supported country to conduct durability monitoring of both PBO-synergist and dual active ingredient nets, in addition to standard pyrethroid nets. The Research Institute of Health Sciences (IRSS) in Bobo-Dioulasso successfully conducted cone bioassays of pyrethroid and PBO nets and tunnel tests with IG2 nets using well-characterized pyrethroid resistant and susceptible colonies of An. gambiae s.l. Experience from baseline tests led to SOP revisions, including a standardized approach to characterization of pyrethroid resistant Anopheles for use in bioassays and increasing the number of positive control new nets to quantify any loss of efficacy more accurately in field nets.
Dr. Gauthier Tougri, Medical Epidemiologist and Program Coordinator for the Burkina Faso NMCP said, “Burkina Faso introduced new generation ITNs [PBO and IG2 nets] for the first time during the universal ITN distribution campaign in 2019. It was therefore timely to conduct this durability study which should allow us to confirm not only that the insecticides used remain effective on existing Anopheles in areas where resistance had been observed, but also that these nets can indeed remain effective during the time interval between distributions.”
In 2021, PMI VectorLink will be conducting durability monitoring studies in 11 countries (Burkina Faso, Burundi, Cote d’Ivoire, Ghana, Liberia, Madagascar, Niger, Rwanda, Sierra Leone, Uganda, and Zambia). In addition, VectorLink will prepare for streamlined durability monitoring activities in Malawi and Nigeria to begin in 2022. VectorLink will draw on its COVID-19 lessons learned to successfully manage these studies: remote training of trainers’ sessions will be conducted to support local study teams, and all in-person trainings and fieldwork will comply with COVID-19 mitigation measures. VectorLink has strengthened in-person training guidelines to further minimize risks to participants and presenters. With advanced COVID-19 planning, all 2021 studies are expected to be conducted on schedule, continuing PMI’s commitment to support NMCPs to generate data on ITN durability.