University of Michigan study shows safety of rotavirus vaccine

A University of Michigan study has shown that despite concerns that rotavirus vaccines might raise infants' risk of blocked bowels, hospitalization rates for the intestinal complication did not go up after vaccination became routine.
One version of the vaccine, which protects babies against diarrheal illness, was first released in the U.S. in 1998 and was pulled the following year after reports of intussusception. This bowel blocking condition occurs when one part of the intestine slides inside another part. Newer versions of the live vaccine didn't link to the bowel problem and rotavirus vaccination was reintroduced in the U.S. in 2007, Reuters reports.
Surveillance for intussusception cases has continued and the study shows that the new vaccine against rotavirus does not cause additional cases.
"The rotavirus vaccine appears to be very safe," Joseph Zickafoose, a scientist at the University of Michigan in Ann Arbor who worked on the study, said, according to Reuters.
Zickafoose and his colleagues consulted a nationally-representative database of children discharged from U.S. hospitals over the decade before the vaccine was re-introduced and one year shortly after. They found that between 1997 to 2006, the number of babies hospitalized for blocked intestines dropped from approximately 42 out of every 100,000 infants to 37 out of 100,000. In 2009, after the vaccine was re-introduced, an estimated 33 out of every 100,000 were discharged after treatment for the bowel problem.
"We expected even with that small amount of risk, we might see something show up after immunization had gotten started (in the U.S.)," Zickafoose said, according to Reuters.
Umesh Parashar, a U.S. Centers for Disease Control and Prevention rotavirus expert, said that the small added risk of intussusception with the vaccine might be hard to pick up in the national study.
"The possibility of a lower-level risk certainly remains," Parashar said, according to Reuters. "I don't think that this analysis alone can prove or disprove an association. It is however reassuring to an extent to see that at least there's no major increase in intussusception."
It is estimated that the vaccine prevents 30,000 to 40,000 infant rotavirus hospitalizations each year. The vaccine is currently recommended for all babies, who receive two or three doses by the time they reach six months of age.