Implementation of the rotavirus vaccination program has significantly reduced the prevalence of rotavirus disease and altered its seasonal patterns in the United States, according to study results published in the Morbidity and Mortality Weekly Report.1

The Centers for Disease Control and Prevention (CDC) analyzed data from 23 laboratories participating in CDC’s National Respiratory and Enteric Viruses Surveillance System that continuously reported rotavirus testing results from July 2000 through June 2018. Because the rotavirus vaccine was introduced in 2006 in the United States, data from July 2006 to June 2007 were excluded from the analysis. Seasonality trend excluded the first 2 reporting years after vaccine introduction (July 2006-June 2008).

Results showed a decline in both rotavirus testing and percent positivity in the postvaccine period (2007-2018) compared with the pre-vaccine period (2000-2006). Compared with the pre-vaccine period, the number of rotavirus tests declined by approximately one-third in the postvaccine period (annual median, 10,845 vs 7357; P <.001), and the number of tests positive for rotavirus declined by approximately 85% (annual median, 2,778 vs 411; P <.001). Similarly, the median annual proportion percentage of tests positive for rotavirus declined 76%, from 25.6% in the pre-vaccine period to 6.1% in the postvaccine period (P <.001).

During peak activity, rotavirus test positivity declined by roughly two-thirds, from an annual median of 43.1% in the pre-vaccine period to 14.0% in the postvaccine period. In addition, the rotavirus season began later in the year in the postvaccine period, with a season duration going from a median of 26 weeks in the pre-vaccine period to 9 weeks in the postvaccine period.

Researchers observed a biennial pattern with alternating years of low and high rotavirus activity in the postvaccine period. They attributed this trend to the low vaccination coverage because the rotavirus vaccine does not offer the same opportunity for catch-up as other childhood vaccines. The first dose of rotavirus vaccine must be given by age 15 weeks, and the series must be completed by age 8 months. Thus, the number of susceptible children accumulating in low rotavirus activity years result in “a higher number of susceptible children and a subsequent rotavirus outbreak during the following season.” Researchers noted that countries like the United Kingdom, which have rapidly achieved and maintained rotavirus vaccination coverage of 90% to 95%, “have experienced a sustained decline in rotavirus activity without the biennial trend observed in the United States.”2

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“To maximize the public health impact of rotavirus vaccination, efforts to improve coverage and on-time vaccination should continue,” concluded the researchers.

References

  1. Hallowell BD, Parashar UD, Curns A, DeGroote NP, Tate JE. Trends in the laboratory detection of rotavirus before and after implementation of routine rotavirus vaccination – United States, 2000-2018. MMWR Morb Mortal Wkly Rep. 2019;68(24):539-543.
  2. Atchison CJ, Stowe J, Andrews N, et al. Rapid declines in age group-specific rotavirus infection and acute gastroenteritis among vaccinated and unvaccinated individuals within 1 year of rotavirus vaccine introduction in England and Wales. J Infect Dis. 2016;213(2):243-249.