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Vaccinations for Diarrhea in Mexico Diarrhea can kill children and is often caused by rotavirus. Read the abstract below, and answer the questions that follow.

“Methods: We obtained data on deaths from diarrhea, regardless of cause, from January 2003 through May 2009 in Mexican children under 5 years of age. We compared diarrhearelated mortality in 2008 and during the 2008 and 2009 rotavirus seasons with the mortality at baseline (2003–2006), before the introduction of the rotavirus vaccine. Vaccine coverage was estimated from administrative data.

Results: Diarrhea-related mortality fell from an annual median of 18.1 deaths per 100,000 children at baseline to 11.8 per 100,000 children in 2008 (rate reduction, 35%; 95% confidence interval [CI], 29 to 39; P  0.001) . . .. Mortality among unvaccinated children between the ages of 24 and 59 months was not significantly reduced. The reduction in the number of diarrhea-related deaths persisted through two full rotavirus seasons (2008 and 2009).

Conclusions: After the introduction of a rotavirus vaccine, a significant decline in diarrhea-related deaths among Mexican children was observed, suggesting a potential benefit from rotavirus vaccination.”

a. State the death rate before vaccine and the death rate after vaccine. What was the change in deaths per 100,000 children? From the given p-value, can you reject the null hypothesis of no change in death rate?

b. Would you conclude that the vaccine was effective? Why or why not?

(Source: R. Vesta et al. 2010. Effect of rotavirus vaccination on death from childhood diarrhea in Mexico. New England Journal of Medicine 62, 299–305.)