Vaccinating babies against a virus that can cause diarrhea and vomiting also seems to protect some adults, a U.S. study suggests.
Rotavirus is a common cause of gastroenteritis in babies, which can result in severe dehydration and admission to hospital.
In Tuesday's online issue of JAMA, researchers from the U.S. Centers for Disease Control and Prevention in Atlanta said they found fewer adults were getting severe cases of gastroenteritis after rotavirus vaccination became standard for infants.
The Canadian Pediatric Society and National Advisory Committee on Immunization recommend that oral vaccines against rotavirus be included in the routine vaccines across the country. British Columbia, Yukon, Saskatchewan, Ontario, Quebec and Prince Edward Island offer it free of charge for babies.
For the study, Dr. Paul Gastanaduy of the CDC and his team looked at the pattern of gastroenteritis hospitalizations among children five years of age or older as well as among adults before and after the vaccine was introduced.
The researchers wanted to see whether indirect protection from reduced transmission of rotavirus extended to adults.
Their answer is yes. Compared with prevaccine years, rotavirus discharges fell for all age groups up to 24 years of age.
"The pattern of observed reductions in gastroenteritis discharges among unvaccinated older children and adults is consistent with indirect protection resulting from infant rotavirus vaccination," the study's authors wrote.
"Based on the observed reductions, annual reductions in gastroenteritis discharges after introduction of rotavirus vaccine in the United States, particularly in the 5- to 44-year-age group, are likely."
For adults, the researchers reviewed discharges for rotavirus as well as gastroenteritis in general since it rotavirus tests are rare for adults, which they said was one of the limitations of the study.
The reductions occurred mainly in March and April — the peak months for rotavirus hospitalization prevaccine, the researchers said. The declines also lasted for three years in a row.