FDA Approves New Vaccine to Prevent Rotavirus Infection

FDA officials recently gave the nod to a second live, oral vaccine designed to protect infants and young children from rotavirus gastroenteritis caused by the G1, G3, G4 and G9 viral strains. Rotarix, which is manufactured by GlaxoSmithKline, is a liquid that is given as a two-dose series to infants between ages 6 and 24 weeks.

The currently available rotavirus vaccine -- a live, oral pentavalent vaccine manufactured by Merck & Co. and marketed as RotaTeq -- is administered in a three-dose schedule at ages 2, 4 and 6 months.

The CDC's Advisory Committee on Immunization Practices, or ACIP, has not yet met to discuss the new vaccine and so has issued no recommendations regarding its use. FP Jonathan Temte, M.D., Ph.D., of Madison, Wis., one of two AAFP liaisons to the ACIP, expects that discussion to take place at the committee's June meeting, with an ACIP vote on a recommendation likely at that time.

The Academy agrees with current ACIP recommendations on rotavirus immunization included in the 2008 Recommended Childhood Immunization Schedule. (1-page PDF; About PDFs) The AAFP Commission on Science will evaluate any forthcoming ACIP recommendations regarding the new vaccine and decide at that time whether to update the Academy's recommendations.

In extensive clinical trials, Rotarix showed no evidence that it increased rates of intussusception in vaccine recipients. Intussusception is a potentially serious adverse effect that in 1999 led to the voluntary withdrawal of a previous rotavirus vaccine marketed in the United States.

However, because one of those clinical trials -- a controlled safety study that involved more than 63,000 infants -- found increased rates of convulsion and pneumonia-related deaths among recipients of the new vaccine, the FDA has directed GlaxoSmithKline to conduct additional postmarketing safety studies. According to an FDA news release, the FDA took that action despite having concluded the available data "do not establish that these events are related to the vaccine."

Specifically, in its April 3 approval letter, the FDA's Center for Biologics Evaluation and Research called on GlaxoSmithKline to perform an observational study involving about 44,000 participants "to assess the potential serious risk of intussusception and other serious adverse effects (specifically Kawasaki disease, hospitalizations due to acute lower respiratory tract infections and convulsions)." That study, the letter went on, should be designed "to detect an increased relative risk of intussusception due to vaccine, with a relative risk of 2.5 or greater and with 80 percent power."

If the results of a national physician survey conducted last year on uptake of Merck's RotaTeq vaccine are any indication, says Temte, it's probably realistic to expect some degree of reticence among family physicians regarding the new Rotarix vaccine. The survey, (21-page PDF; About PDFs) which was sponsored by the CDC's National Center for Immunization and Respiratory Diseases, found that, compared with pediatricians, FPs were slightly more than half as likely to routinely offer rotavirus vaccine to eligible patients (85 percent versus 45 percent).

"This reluctance to use a safe and effective vaccine is unfortunate," Temte says, "because rotavirus is a leading cause of preventable illness, clinic visits, emergency room visits and hospitalizations in our youngest patients."

The October 2007 survey identified a number of perceived barriers to giving the rotavirus vaccine among the physicians surveyed. Those barriers included

It's something of a hallmark of family medicine, says Temte, to not be too quick to hop on the latest clinical practice bandwagon. "FPs have a long tradition of being a bit slow on the uptake of new vaccines and other interventions," he notes. "This is neither good nor bad; rather, I think it says something about the specialty's focus on patient-centeredness (waiting until new interventions are shown to be safe and effective) and the lack of a forceful central policy committee for vaccines in family medicine settings, such as the Committee on Infectious Diseases at the American Academy of Pediatrics."