Time trends in diarrhea mortality in Mexican children under-5: Impact of various interventions including water, sanitation, and the rotavirus vaccine

Diarrhea is the second leading cause of mortality in children under-5 worldwide. Many of these deaths can be prevented by oral rehydration therapy (ORT), improved water/sanitation, and rotavirus vaccine. In Mexico, diarrhea deaths in children under-5 have decreased dramatically over the past 3 decades as the country transitioned from lower to upper middle class economy. We set out to map the mortality reduction achieved with various public health interventions, using Mexico vital statistics, 1979-2009. Diarrheal mortality rates decreased 40-fold over the 3 decades. A distinct seasonal pattern of dramatic summer seasonality occurred in the first decade (consistent with bacterial diarrhea), but by early 1990s these summer peaks disappeared, revealing modest winter peaks consistent with rotavirus seasonality. The annual diarrheal mortality reduction temporally associated with ORT introduction in 1984, water/sanitation improvements during 1989-1999, and rotavirus vaccine introduced in 2007 was 58.8/100,000, 30.5/100,000, and 6/100,000, respectively. The rotavirus vaccine introduction in 2007, while halving the residual winter diarrhea mortality, contributed only modestly to the absolute gains in diarrheal reduction. Had the vaccine been introduced around 1980 we compute it could maximally have reduced ~18% of the large diarrhea burden at the time. We conclude that developing and lower middle class countries considering introducing the rotavirus vaccine should weigh the costs of the program against costs of introducing more universal diarrhea reduction strategies that address both summer and winter diarrhea.