Estimation of bed net coverage indicators using a national mobile phone survey in Tanzania

Abstract Background: Monitoring and surveillance of bed net coverage indicators is critical, particularly due to threats in maintaining high population access to effective bed nets, but usually occurs every 2-3 years through large-scale national household surveys. However, the rapid growth of mobile phone ownership in Tanzania has resulted in mobile phone-based survey methodologies emerging as an alternative to household surveys. Methods: A national mobile phone survey was conducted in early 2021 with focus on bed net ownership and access. Half of the sample target was contacted through a standard random digit dial methodology and the remaining half was reached through a voluntary opt-in respondent pool. Both sampling approaches used an interactive voice response survey conducted in Kiswahili. Results: The response rate was approximately 1.5% across the combined sampling approaches. Population access (i.e., the percent of the population that could sleep under a bed net, assuming one bed net per two people) varied from a regionally adjusted low of 48.1% (Katavi) to a high of 65.5% (Dodoma). The adjusted percent of households that had a least one bed net ranged from 54.8% (Pemba) to 75.5% (Dodoma); the adjusted percent of households with at least one bed net per 2 de facto household population ranged from 35.9% (Manyara) to 55.7% (Dodoma). The estimates produced by both sampling approaches were generally similar, differing by only a few percentage points. An analysis of differences between estimates generated from the two sampling approaches showed minimal bias when considering variation across the indicator for households with at least one bed net per two de facto household population. Conclusion: Mobile phone surveys can provide rapid estimates of bed net coverage in Tanzania and may serve as a suitable source of information between large-scale household surveys. The results generated by this survey show that overall bed net access in the country appears to be lower than target thresholds. The results suggest that bed net distribution is needed in large sections of the country to ensure that coverage levels remain high enough to sustain protection against malaria for the population.