Rotavirus hospitalizations down by 86% with vaccine

The rotavirus vaccine introduced in early 2006 has worked as intended, cutting the US rate of rotavirus associated diarrhea requiring hospitalization in children younger than 2 years by 86 percent during July 2007-June 2008, compared with rates during 2000-2006, according to an analysis of a large US private insurance database.

“The first rotavirus season post vaccine introduction showed a substantial decline, to a level below the lowest rate of prior years,” reported at the annual meeting of the Infectious Diseases Society of America. “The reduction was lower than in the clinical trials, where vaccine effectiveness was more than 95 percent, but it was still effective in the real world,” said an epidemic intelligence service officer in the division of viral diseases of the Centers for Disease Control and Prevention.

The data also showed a significant impact of rotavirus vaccination on the incidence of all diarrhea that led to hospitalization in children younger than 2 years during July 2007-June 2008, cutting this rate by 39 percent, compared with the average during 2000-2006.

Experience using the rotavirus vaccine since its US introduction more than 3.5 years ago confirms its safety, with no unexpected reports of vaccine-associated adverse effects and no link with excess cases of intussusception, the adverse effect that torpedoed the first rotavirus vaccine, RotaShield.

The data reported reflected a time period when rotavirus vaccination was overwhelmingly done via the RotaTeq formulation, introduced in early 2006. Last year, a second vaccine, Rotatrix, came onto the US market.

Analyzed data collected in the MarketScan claims-based database, which collects data on a subset of privately insured US residents. The database included records for about 2 million children younger than 5 years for the period 2007-2008.

The data showed that after RotaTeq’s US introduction, its use in children younger than 1 year gradually rose, reaching 63 percent coverage of children 11 months or younger by the end of December 2007. The recommended US schedule for administering RotaTeq is at 2, 4, and 6 months of age, with no allowance for catch up vaccination if one or more of these doses are missed.

With vaccine coverage at 63 percent during the midpoint of the July 2007-2008 rotavirus season studied, the 86 percent vaccine effectiveness rate seen was “greater than expected.” The data also showed that hospitalization for rotavirus-associated diarrhea was reduced in older children, 2-4 years old, who never received rotavirus vaccination. These findings suggest a herd effect, a hypothesis now being studied by the CDC.

Laboratory surveillance data for the period July 2008-June 2009 indicated that the benefits seen in the 2007-2008 season continued into the most recent rotavirus season.