Rotavirus Vaccine Benefits Extend Beyond Immediate Targets

Norra MacReady

August 27, 2013

The incidence of severe gastroenteritis has declined significantly among children younger than 5 years since the rotavirus vaccine was introduced in 2006. Data now show that older age groups have also had significant reductions of severe gastroenteritis, suggesting the vaccine's benefits extend beyond its original recipients.

Paul A. Gastañaduy, MD, MPH, and colleagues report the results of their analysis in a research letter published in the August 28 issue of JAMA.

The rotavirus vaccine was introduced in the United States in 2006. The current recommendations from the Centers for Disease Control and Prevention include administration of vaccines to infants under the age of 2 years.

Dr. Gastañaduy, from the Division of Viral Diseases, CDC, and coauthors analyzed rotavirus-coded and cause-unspecified gastroenteritis discharges from January 2000 through December 2010, using data from the Nationwide Inpatient Sample, a nationally representative database of hospital inpatient stays. They estimated annual and monthly incidence rate ratios for the prevaccine years 2000 through 2006 and for each postvaccine year from 2008 through 2010, controlling for month, secular trends, and population size. The researchers excluded 2007, which is considered a transitional year with limited coverage.

Compared with the prevaccine era, significant reductions in rate ratios (RR) of rotavirus-coded gastroenteritis occurred in the 0- to 4-year age group (RR, 0.20; 95% confidence interval [CI], 0.14 - 0.28; P < .001), those aged 5 to 14 years (RR, 0.30; 95% CI, 0.21 - 0.44; P < .001), and those aged 15 to 24 years (RR, 0.47; 95% CI, 0.24 - 0.94; P = .03). Significant reductions in cause-unspecified gastroenteritis were seen at 0 to 4 years of age (RR, 0.58; 95% CI, 0.50 - 0.66), age 5 to 14 years (RR, 0.70; 95% CI, 0.65 - 0.76), age 15 to 24 years (RR, 0.89; 95% CI, 0.84 - 0.95), and age 25 to 44 years (RR, 0.94; 95% CI, 0.90 - 0.98; P < .001 for all comparisons with the prevaccine years).

For all age groups, these reductions were concentrated in the late winter and early spring months of the postvaccine years, with significant reductions also occurring in March and April 2010. These months were the period of peak hospitalization for rotavirus infection in the prevaccine era, the authors write. They observed significant reductions among all ages in 2010, "which is when the greatest decline in rotavirus hospitalizations among vaccine-eligible young children occurred."

The study limitations include its ecological design, lack of information about the cause-unspecified charges, and infrequent use of the rotavirus codes among adults, although this would result in bias only if coding practices changed over time, the authors write.

The reductions coincided with increasing vaccine coverage and "illustrate how indirect benefits may amplify the effect of the US rotavirus vaccination program," they conclude.

The authors have disclosed no relevant financial relationships.

JAMA. 2013;310:851-853.

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