SAN DIEGO – Rhode Island’s universal vaccine policy led to widespread vaccination against rotavirus, steep drops in pediatric hospitalizations for gastroenteritis, and major shifts in circulating rotavirus genotypes, investigators reported at an annual scientific meeting on infectious diseases.
“Vaccination with both RV5 (RotaTeq) and RV1 (Rotarix) decreased rotavirus disease in Rhode Island,” said Dr. Sabina Holland, who led the single-center, prospective study at Hasbro Children’s Hospital, Brown University, Providence, R.I. “Variations in genotype distribution and the emergence of uncommon strains occurred only after introduction of RV1,” she and her associates reported.
Dr. Sabina Holland
Rotavirus, the leading cause of severe diarrhea worldwide, was implicated in 453,000 deaths in 2008 alone, Dr. Holland noted. The Rhode Island health department gives pediatric vaccines to health care providers free of charge, and as a result, rotavirus vaccine coverage in the state is about 89%, she said.
To understand the effects of this high vaccination rate, Dr. Holland and her associates conducted active surveillance for hospitalizations of children younger than 10 years old with gastroenteritis between 2002 and 2012. Between 2012 and 2015, they performed passive laboratory surveillance by testing stool samples for rotavirus with a commercially available enzyme immunoassay. They also used reverse transcription polymerase chain reaction (RT-PCR) to genotype rotavirus RNA. Finally, they examined vaccination records of cases from the state immunization registry for the years 2009-2015, Dr. Holland said at the combined annual meetings of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association, and the Pediatric Infectious Diseases Society.
The hospital admitted between 79 and 159 children every year with rotavirus disease between 2002 and 2006, and there was no overall upward or downward trend during this period, said Dr. Holland. Hospitalizations for rotavirus then dropped by about 50% 1 year after RV5 was introduced, she said. Hospitalizations kept dropping every subsequent year until 2014, when the hospital admitted only one child with rotavirus disease.
But, in 2015, the hospital admitted six children for rotavirus disease, including three who had not received RV1 or RV5, Dr. Holland said. “We need to continue surveillance to see if the increase in hospitalizations in 2015 will continue, and if it is related to genotype variation secondary to vaccine-induced immune pressure, or due to natural variation,” she added.
Genotype 1 rotavirus, which is most common globally, predominated until after Rhode Island implemented RV5, the study found. Genotype 2 prevailed in 2010, when the state switched to RV1. Since then, nontypeable strains have predominated, and the research team is continuing to sequence them.
The National Science Foundation partially supported the research with a grant to the University of Rhode Island Genomics and Sequencing Center in Kingston. The Center for International Health Research also helped with analyses. Dr. Holland reported no relevant financial disclosures. Senior author Dr. Penelope Dennehy reported receiving relevant research funding from Merck, the maker of RotaTeq.