Statewide universal vaccine policy reduced rotavirus strains, hospitalizations

MEMPHIS, Tenn. — Implementation of a universal pentavalent rotavirus vaccine in Rhode Island significantly reduced the number of rotavirus-associated hospitalizations and strains of rotavirus circulating in the community, according to data presented at the St. Jude/PIDS Pediatric Infectious Diseases Research Conference.

Rhode Island law requires the Department of Health to provide routine childhood immunization for children as recommended by the AAP and the CDC’s Advisory Committee on Immunization Practices, regardless of insurance status.

“This policy means that in 2006 to 2009, we can track exclusive use of the pentavalent rotavirus vaccine, followed by a brief period of mixed use, and then in 2010 exclusive use of the monovalent vaccine,” Sabina D. Holland, MD, from Hasbro Children’s Hospital in Providence, Rhode Island, told Infectious Diseases in Children. “Combined with the above-average vaccine coverage rate in Rhode Island, this data provided us with a very unique opportunity to look at the impact of vaccination on disease and rotavirus distribution.”

To distinguish circulating rotavirus genotypes before and after initiation of rotavirus vaccination in the state, Holland and colleagues used active hospital-based surveillance to identify patients aged younger than 10 years admitted with gastroenteritis from 2002 through 2012.

From 2012 to 2014, cases were identified if a stool sample was referred for rotavirus testing, using a commercially available enzyme immunoassay. The researchers extracted viral RNA and performed VP7 genotyping using semi nested reverse transcription PCR for primers specific for G1, G2, G3, G4 and G9 genotypes.

Among 835 rotavirus-positive stools, 91% were available for genotyping; of those, 7% were nontypeable.

According to data, implementation of rotavirus vaccine decreased the number of annual rotavirus cases from a mean of 127.5 (before the vaccination policy) to one case in 2014.

“What we found was that with the introduction of the pentavalent vaccine in 2006 you have this dramatic decline in the admission rate that continued falling until the current year of 2014,” Holland said. “What is more fascinating is that even prior to the introduction of the vaccine, we can see that G1 is the predominant genotype.”

The researchers said G1 genotype was the predominant genotype in all but 1 year before rotavirus vaccine introduction and remained the principal genotype for several years after introduction of pentavalent rotavirus vaccine in 2006 (87%, 70%, 84%, 38%). After introduction of monovalent vaccine in 2010, the predominant genotype was G2 (90%).

“These results have led us to conclude that rotavirus vaccination has decreased admissions for rotavirus, and that we continued to see variation after the implementation of the monovalent vaccine,” Holland said. “What we need to do is continue surveillance, possibly expanding this to include outpatient sites — including emergency room and urgent care centers — where we know that physicians are seeing disease, but simply not testing for them, and then genotype those to determine if there is any variation.” – by Bob Stott

Reference:

Holland SD, et al. Abstract R201524. Presented at: St. Jude/PIDS Pediatric Infectious Diseases Research Conference; Feb. 20-21, 2015; Memphis, Tennessee.

Disclosure: The researchers report no relevant financial disclosures.