After implementation of routine rotavirus vaccination in the United States in 2006, there has been a sustained decrease in laboratory detection, according to a report from the Centers for Disease Control and Prevention, published in the April 9 issue of the Morbidity and Mortality Weekly Report.

"Before the introduction of rotavirus vaccine in the United States in 2006, rotavirus infection caused significant morbidity among U.S. children, with an estimated 55,000–70,000 hospitalizations and 410,000 clinic visits annually," write Negar Aliabadi, MD, from the Epidemic Intelligence Service and Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, and colleagues.–

In 2006, rotavirus vaccine was first included in the childhood vaccination schedule. Subsequently, there was a substantial, sustained decline in rotavirus circulation both nationally and regionally, as well as a shift in the epidemiology of this virus.

During reporting years 2007 to 2014, data from the National Respiratory and Enteric Virus Surveillance System indicate a 57.8% to 89.9% national decline in disease activity for each postvaccine year compared with prevaccine years, with alternating years of lower and greater positivity rates. Analysis of data for each region revealed similar patterns.

Additional benefits after routine vaccination against rotavirus included delay or absence of rotavirus seasons, with shorter duration (0 - 18 weeks) and lower peak positivity for rotavirus (10.9% - 27.3%).

"The later onset and shorter duration of rotavirus seasons in the postvaccine era, including some years without a defined rotavirus season, could be a result of fewer unvaccinated, susceptible infants, resulting in reduced intensity and duration of rotavirus transmission," the report authors write. "This reduced transmission of rotavirus likely also explains the declines in rates of rotavirus disease that have been seen in unvaccinated older children and even in some adult age groups in postvaccine years compared with the prevaccine era, resulting from the phenomenon known as herd immunity."

The authors note several study limitations, including reliance on aggregate reports of stool samples without any demographic or clinical data, possible regional biases, possible variations in testing practices from site to site and year to year, and possible changes in rotavirus testing practices coinciding with implementation of the rotavirus vaccination program.

The report authors estimate that during 2007 to 2011, routine rotavirus vaccination averted more than 176,000 hospitalizations, 242,000 emergency department visits, and 1.1 million outpatient visits resulting from diarrhea, with cost savings of $924 million. They anticipate additional reductions in rotavirus disease burden from 2012 to 2014.

"The findings in this report are consistent with the high field effectiveness of vaccination observed in post-licensure epidemiologic studies," the report authors conclude. "Taken together, these findings reaffirm the large public health impact of routine rotavirus vaccination in reducing the circulation of rotavirus among U.S. children."

The authors have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. 2015;64:337-342. Full text