Is the intention to vaccinate enough? Systematic variation in the value of timely vaccinations and preferences for monetary vs non-monetary incentives among pregnant women in southern Tanzania.

Background: Globally, approximately 19.7 million children remain under-vaccinated; many more receive delayed vaccinations. Sustained progress towards global vaccination targets requires overcoming, or compensating for, incrementally greater barriers to vaccinating hard-to-reach and hard-to-vaccinate children. We prospectively assessed pregnant women's valuations of routine childhood vaccinations and preferences for alternative incentives to inform interventions aiming to increase vaccination coverage and timeliness in southern Tanzania. Methods: Between August and December 2017, 406 women in their last trimester of pregnancy were enrolled from health facilities and communities in the Mtwara region of Tanzania and asked contingent valuation questions about their willingness to vaccinate their child if they were (a) given an incentive, or (b) facing a cost for each vaccination. Interval censored regressions assessed correlates of women's willingness to pay (WTP) for timely vaccinations. Participants were asked to rank monetary and non-monetary incentive options for the timely vaccination of their children. Findings: All women expected to get their children vaccinated according to the recommended schedule, even without incentives. Nearly all women (393; 96.8 %) were willing to pay for vaccinations. The average WTP was Tanzania Shilling (Tsh) 3,066 (95 % confidence interval Tsh 2,523-3,610; 1 USD ∼ Tsh 2,200) for each vaccination. Women's valuations of timely vaccinations varied significantly with vaccine-related knowledge and attitudes, economic status, and rural vs urban residence. Women tended to prefer non-monetary over monetary incentives for the timely vaccination of their children. Interpretation: Women placed a high value on timely childhood vaccinations, suggesting that unexpected system-level barriers rather than individual-level demand factors are likely to be the primary drivers of missed vaccinations. Systematic variation in the value of vaccinations across women reflects variation in perceived benefits and opportunity costs. In this setting, nonmonetary incentives and other interventions to increase demand and compensate for system-level barriers hold significant potential for improving vaccination coverage and timeliness. ClinicalTrialsgov Protocol: NCT03252288.