“We looked at the impact of the vaccine over four consecutive vaccine years,” said lead author Dr. Eyal Leshem of the Centers for Disease Control and Prevention (CDC) in Atlanta. “The dramatic decline we saw at the beginning has continued.”
Rotavirus commonly causes severe diarrhea and hospitalization in the U.S., and is responsible for the deaths of between 20 and 60 children per year, Leshem told Reuters Health.
In countries where access to healthcare is lower, the situation is even more serious.
“Worldwide, about 450,000 children died each year due to rotavirus before a vaccine was licensed,” said Dr. Evan Anderson, who studies rotavirus infection at Emory University School of Medicine in Atlanta.
“The virus is spread by contact with infected stool, usually by fecal-oral transmission, and it is incredibly infectious,” Anderson, who was not involved in the new study, told Reuters Health by email. “About 10 billion viral particles exist in a gram of stool and only about 100 are needed to cause infection.”
Older children and adults can also develop life-threatening rotavirus infections, he noted.
The initial rotavirus vaccine was introduced in the U.S. in 1998 and pulled the following year due to concerns it might cause blocked bowels in babies.
After a new vaccine became available, the U.S. Advisory Committee on Immunization Practices recommended in 2006 that all children be vaccinated against rotavirus, which entails three vaccine doses given by mouth at two, four and six months of age. In 2008 a two-dose vaccine became available as well.
Testing of the newer vaccines has not shown the same bowel-related side effects.
Leshem and his coauthors found that among more than 400,000 children from 37 states, 64 percent of those less than one year of age had been vaccinated in 2007, which rose to 78 percent by 2010.
According to information from an insurance claims database for the years 2001 through 2011, there was no change in the rates of hospitalizations or outpatient pediatric visits for diarrhea between 2001 and 2006.
Compared with those rates, rotavirus hospitalizations dipped by 75 percent in 2007. Between 2007 and 2011, the yearly rate of hospitalizations remained at least 60 percent lower than it had been in 2006, according to results published in Pediatrics.
The vaccine also seemed to help protect kids who had not been vaccinated, as their rate of rotavirus-related hospitalizations decreased by 50 percent in 2007. That reflects the knowledge that when a certain proportion of children are vaccinated, there is less of the virus circulating in the population and less chance other kids will catch it, a concept known as “herd immunity.”
The authors estimate that 177,000 hospitalizations, 242,000 emergency room visits and more than a million outpatient visits for diarrhea among children under age five were avoided between mid-2007 and mid-2011, due to the rotavirus vaccine.
That equates to $924 million in savings for the U.S. healthcare system, they write.
“One of the interesting findings we had was in one of the later years we saw a 94 percent decrease in hospitalization; rotavirus had practically disappeared in 2010,” Leshem said. “This is attributed to good vaccine effectiveness and high coverage.”
The rotavirus vaccine seems to be similar to the measles vaccine, he said, in that once the vaccine becomes common the infection almost goes away completely.
But the rate of vaccination against rotavirus is still much lower than rates for other recommended vaccines, Anderson said.
“Unfortunately, there is a limited window during infancy for receiving the vaccine so a number of children are not able to receive the vaccine or are not completely vaccinated,” he said.
For certain kids, like those with immune deficiencies, rotavirus vaccines are not recommended, but for most the benefits well outweigh the risks, Leshem said. If there are any side effects of the vaccines, they are very mild, he said.
“I would urge all parents to discuss this with their provider,” Leshem said.
“Not only does receiving the vaccine benefit their children, it also helps to protect other infants who are unable to receive rotavirus vaccination due to their underlying medical conditions,” Anderson said. “The findings of this study are good news for everyone.” (Reuters)