(RxWiki News) One of the most common reasons for diarrhea among children is rotavirus. But a vaccine for rotavirus was introduced in 2007.
A recent study found that the numbers of diarrhea-related illnesses in the US dropped after the vaccine was introduced.
In fact, the rate of hospitalizations related to rotavirus dropped in both vaccinated and unvaccinated children.
That finding means that the increasing levels of vaccination put a dent in the ability of the virus to travel through the population.
"Discuss vaccinations with your child's pediatrician."
The study, led by Eyal Leshem, MD, of the National Center for Immunization and Respiratory Diseases at the US Centers for Disease Control and Prevention, looked at the numbers of diarrhea-related illnesses after the rotavirus vaccine was introduced.
The authors used insurance claims data for all children under 5 years old to determine how many diarrhea-related illness occurred between 2001-2006 (before the vaccine was used) and 2007-2011.
They also compared how much healthcare was used for diarrhea-related reasons among both vaccinated and unvaccinated children.
This latter analysis included looking at the rates of diarrhea-related illness in unvaccinated children both before and after the vaccine was introduced.
Understanding the rates before and after the vaccine was introduced even in unvaccinated children could offer clues about the effectiveness of herd immunity.
Herd immunity is the concept that members of a population are protected from a disease when enough of that population is vaccinated against it to prevent it from spreading throughout the group.
First, the researchers determined that 58 percent of children had been vaccinated against five strains of rotavirus by the end of 2010.
Then they found that rotavirus-related hospitalizations were 75 percent lower in 2007-2008 than they were from 2001-2006.
Compared to 2001-2006 rates, rotavirus cases had were 60 percent lower in 2008-2009, 94 percent lower in 2009-2010 and 80 percent lower in 2010-2011.
When the authors looked only at children who had been vaccinated against rotavirus, hospitalization rates related to the virus were 92 percent lower in 2010-2011 than they had been in the years before the vaccine was introduced.
Among the 5 percent of children who received only the RV1 vaccine—protecting against one strain—the rate of rotavirus-related hospitalizations was 96 percent lower in 2010-2011.
Similarly large drops were seen when the researchers compared vaccinated to unvaccinated children.
Among 1-year-olds, for example, 87 percent fewer rotavirus-hospitalizations occurred among vaccinated children than among unvaccinated children.
Among 4-year-olds, the rate was 81 percent lower for those who had been vaccinated.
However, it appears that herd immunity was effective in helping to reduce the disease even in those who were not vaccinated.
Among unvaccinated children, the rate of rotavirus-related hospitalizations in 2007-2008 was 50 percent lower than it was from 2001 to 2006, before the vaccine was introduced.
The rate for unvaccinated children was 77 percent lower in 2009-2010 than in the years before the vaccine was introduced, and it was 25 percent lower in 2010-2011.
"Implementation of rotavirus vaccines has substantially reduced diarrhea health care utilization in US children," the authors wrote. "Both rotavirus vaccines conferred high protection against rotavirus hospitalizations."
The study was published June 9 in the journal Pediatrics. The research did not use external funding. The authors reported no conflicts of interest.