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Herd immunity has extended the benefits of several vaccines, including the childhood Haemophilus influenzae B and pneumococcal vaccines, far beyond the target populations. Investigators at the CDC have now found evidence that infant rotavirus vaccination — introduced in the U.S. in 2006 — is having a similar effect.
Using the Nationwide Inpatient Sample — a nationally representative database of U.S. hospitalizations — the researchers identified hospitalizations for rotavirus and cause-unspecified gastroenteritis from January 2000 through December 2010. Compared with the prevaccine period, 2008–2010 showed a significant reduction in hospitalizations for rotavirus gastroenteritis among individuals aged ≤24 years, and in hospitalizations for cause-unspecified gastroenteritis among those aged ≤44 years. In 2010, hospitalizations were significantly reduced across all age groups for both rotavirus and cause-unspecified gastroenteritis.
Gastañaduy PA et al. Gastroenteritis hospitalizations in older children and adults in the United States before and after implementation of infant rotavirus vaccination. JAMA 2013 Aug 28; 310:851. (http://dx.doi.org/10.1001/jama.2013.170800)
Comment
The authors acknowledge limitations of their study, including use of hospital discharge coding data and the lack of specificity of cause-unspecified gastroenteritis. However, the results were consistent over 3 consecutive years, and the reductions were most pronounced during the months of March and April, when rotavirus hospitalizations peaked in the prevaccine period. These findings suggest a major role for childhood transmission in the epidemiology of rotavirus and highlight the broad public health benefits of national vaccine programs.