Rotavirus Vaccine Danger Questioned

Government study finds no increase in bowel-blockage complication in babies as a result of shot

THURSDAY, Oct. 11, 2001 (HealthDayNews) -- A government study raises a disturbing question: Was the right decision made when a vaccine against childhood diarrhea was taken off the market because of a small number of serious side effects?

Two years ago, that vaccine, Rotashield, was withdrawn because it was linked to a potentially fatal bowel blockage in some children. But now federal epidemiologists report they found a slight decrease in hospital admissions for that complication during the 10 months when a million American children received the vaccine.

The Rotashield vaccine was approved by the Food and Drug Administration in August 1998 for protection against rotavirus, which is responsible for 50,000 hospital admissions and 20 deaths among children each year in the United States. Its production and use was stopped in July 1999, when the Centers for Disease Control and Prevention reported 15 cases of intussusception, a life-threatening bowel blockage, in children who received the vaccine.

But a 10-state study of more than 1 million children, more than a quarter of whom got at least one shot of the vaccine, finds a slight reduction in hospital admissions for infants with intussusception during the time when the vaccine was used, compared to the same period a year earlier. The study was done by a group led by Lone Simonsen, an epidemiologist at the National Institute of Allergy and Infectious Diseases, and appears in the Oct. 13 issue of The Lancet.

"The CDC did the right thing in calling attention to the problem," Simonsen says. "They did prove there was a causal link. But I do think they overestimated the risk. They have since come down by 50 percent, and our paper takes it a step further."

The overall increased risk of intussusception among infants receiving the virus is one extra hospital admission for every 66,000 to 302,000 children, the journal report says.

One theory is that the vaccine is an early trigger for children who are susceptible to the condition, she says, so that the overall incidence does not increase. Another is that while the vaccine can cause intussusception after it is first given, it prevents the condition caused by natural rotavirus infection later in infancy.

The new study is not perfect, Simonsen acknowledges. Specifically, it does not compare the risk of intussusception among children who got the vaccine and those who did. Plans for such studies are under way, she adds.

Meanwhile, Simonsen says, "We have to come to terms with what we do with very low levels of risk. We have a very, very risk-adverse climate in the United States."

The incidence of childhood rotavirus infections has returned to the pre-vaccine level, she notes, meaning that 20 children will die each year of the infection. Because of prompt treatment of intussusception, "this vaccine did not cause one death," Simonsen says.

Thought should also be given to the global rotavirus issue, says Dr. Bruce Gellin, professor of medicine at Vanderbilt University and executive director of the National Network for Immunization Information. He says the new study "underscores the efforts to which the immunology community is concerned about providing vaccines that have the best safety profile."

"From 600,000 to 800,000 children worldwide die of rotavirus infections each year," Gellin adds. "We have a level of concern about the safety of the vaccine, but how can we take the next step forward? What level of risk are people willing to tolerate for a known benefit?"

The rotavirus vaccine gap will not be closed soon, Simonsen says. "There are better vaccines in the pipeline, but they are years away," she says.

Resumption of Rotashield production is highly unlikely even though the vaccine still has FDA approval, says Doug Petkus, a spokesman for Wyeth-Ayerst Laboratories, which marketed the product.

"We have no particular plans to reintroduce the product to the marketplace," Petkus says. "We've not been asked to do so by anyone, and if we were contacted, we would have to conduct a series of studies before making a decision. From a research perspective, this is an important disease, but we have no program in place that is advanced enough to share information."

What To Do

Parents can follow the sanitary rules designed to reduce the risk of viral infection and can be alert to the need to consult a doctor when a child experiences severe diarrhea.

Information about rotavirus infection is offered by the Centers for Disease Control and Prevention. Learn more about vaccines in general from the CDC's National Immunization Program or the National Network for Immunization Information.

SOURCES: Interviews with Lone Simonsen, Ph.D, epidemiologist, National Institute of Allergy and Infectious Diseases, Bethesda, Md.; Bruce Gellin, professor of medicine, Vanderbilt University, Nashville, Tenn.; Doug Petkus, spokesman, Wyeth-Ayerst Laboratories, Radnor, Pa.; Oct. 13, 2001, The Lancet
Consumer News