Heat-Stable Oral Rotavirus Vaccine.

To the Editor: Isanaka and colleagues (March 23 issue)1 tested a heat-stable rotavirus vaccine in Niger and report an efficacy of 66.7% against severe rotavirus gastroenteritis in the per-protocol population. The purpose of rotavirus vaccination is ultimately to reduce the incidence of diarrhea and diarrhea-related death. However, the rate of severe gastroenteritis due to any cause was not significantly lower among the vaccinated infants than among those who received placebo (difference in rate, 1.97 cases per 100 personyears; 95% confidence interval [CI], −1.28 to 5.22). The lack of efficacy against severe gastroenteritis has not been highlighted in the discussion although this information is crucial for decision makers. The intention-to-treat analysis more closely reflects efficacy in real-world conditions. Everyone who received the first dose of vaccine was included in the intention-to-treat analysis; 86% of them went on to receive all three doses per the protocol and were included in the per-protocol analysis. In the intention-to-treat analysis, there was a significantly higher rate of gastroenteritis due to any cause in the vaccine group than in the placebo group (difference in rate, −6.59 cases per 100 person-years; 95% CI, −11.89 to −1.29 [negative difference values favor the placebo group]). Again, there was no benefit of the vaccine against severe gastroenteritis. This vaccine could aggravate the problem it is meant to solve in resource-poor countries.