Modeling the impact of geographic targeting of rotavirus vaccination in India on rotavirus diarrhea mortality in children under 5 years of age

Thesis (Master's)--University of Washington, 2020Background: Rotavirus causes around 329,000 diarrhea deaths annually around the world, almost a third of which are in India. The rotavirus vaccine is a relatively recent but important vaccine; an India-manufactured rotavirus vaccine was licensed for use in India in 2014. A total of 15 out of 31 Indian states and union territories have substantial rollout of this vaccine, while the remainder are just beginning to deploy the vaccine as of 2019. Targeting vaccination deployment to areas based on disease burden has been found to be more cost-effective than population-based deployment in Sub-Saharan Africa; this study seeks to explore this concept of geographic targeting of vaccinations in India. Quantifying the potential impact of various rotavirus vaccination targeting strategies on mortality in the states and union territories of India from 2020-2040 is key to determining the best strategies for vaccine rollout as these states begin to scale-up coverage. Methods and Findings: The objective of this study was to simulate different vaccination scenarios and quantify their impact on mortality, compared to a reference scenario based on historical vaccine coverage. The reference scenario is the mean of the observed rotavirus vaccine scale-up in the 15 states that have already introduced the vaccine in substantial numbers. The other three scenarios add the same number of vaccines on top of the reference scenario, but distributed in different ways. One scenario simply distributes the extra vaccines according to population in each state (population-based), one distributes based on diphtheria-tetanus-pertussis (DTP3) vaccine coverage (target DTP3 coverage), and the other distributes based on rotavirus diarrhea mortality rate levels (target rotavirus mortality). These vaccine scenarios were used to estimate under-5 rotavirus diarrhea mortality rates from 2020-2040 while holding other drivers of health to recent trends. In this study, approximately 163 million more vaccinations than in the reference scenario were distributed in each of the targeting scenarios. A total of 151,001 (59,343, 302,650) under-5 deaths from 2020-2040 were estimated in the reference scenario, compared to 125,050 (48,272, 251,358) in the population-based scenario, 119,260 (45,686, 240,953) in the DTP3 targeting scenario, and 116,152 (44,278, 234,991) in the rotavirus targeting scenario. The highest number of averted deaths is most likely to be achieved by using the strategy of vaccine distribution according to past rotavirus diarrhea mortality. Conclusions: This study suggests that geographic targeting based on historical disease burden would lower the number of deaths from rotavirus diarrhea seen in India from 2020-2040. As India progresses in advancing rotavirus vaccination, it is key to consider the distribution strategy of these vaccines. Targeting based on disease burden could lower the number of deaths seen from rotavirus diarrhea by thousands compared to distributing according to population. The largest reduction in deaths is seen in the next few years, making swift action in high-burden areas essential