FDA considers vaccine against dangerous diarrheal infection in infants

Tuesday, December 13th 2005, 5:41 pm

By: News On 6

WASHINGTON (AP) _ A new vaccine against a sometimes deadly diarrheal infection in infants does not appear to cause the problems associated with an earlier vaccine, though the government says it needs more information.

A Food and Drug Administration reviewer wrote that RotaTeq, drug company Merck & Co.'s vaccine against rotavirus, is ``highly likely'' to be effective based on the results of a study that showed a decrease in rotavirus-caused illness.

The FDA is seeking additional information from Merck before reaching conclusions on the second study, according to documents posted Tuesday on the agency's Web site. A Merck spokeswoman said the company has supplied all requested data to the FDA.

In the United States, rotavirus infects many children before their third birthday, sometimes resulting in hospitalization. The virus kills several dozen American children a year. Children eventually develop an immunity.

The virus' effects in developing countries, however, are much more severe, and it is blamed for millions of deaths.

An expert FDA advisory panel is expected to discuss the experimental treatment Wednesday. The agency and its advisers may be cautious about approving it in the face of problems tied to an earlier vaccine, RotaShield. It was pulled in 1999 by manufacturer Wyeth after 20 out of 1 million infants developed a potentially fatal twisted bowel condition within a month of receiving it.

But researchers looked closely for cases of children developing the condition, called intussusception, in the RotaTeq trials studied by the FDA, and found it did not occur more often than it did in children who received a placebo instead of the vaccine.

The vaccine would be given to infants as a liquid during regular vaccinations at the ages of two, four and six months.

Dr. Penny Heaton, who helped develop the vaccine for Merck, said the company's studies show the vaccine reduced gastrointestinal illness caused by rotavirus by 74 percent in infants in the first year after taking the vaccine, when compared to those given a placebo. It reduced severe cases of the illness by 98 percent.

In infants studied for a second year after taking the vaccine, gastrointestinal illness caused by rotavirus was reduced by 62 percent compared to placebo; severe cases were reduced by 88 percent, Heaton said.

Company officials said the vaccine is meant to be effective for two years, because an older child who gets rotavirus is much less vulnerable to dehydration and other severe consequences of the illness, and therefore less likely to need hospitalization. Children would still probably catch rotavirus and develop natural immunities to it.

A third vaccine, GlaxoSmithKline's Rotarix, has been licensed in Mexico but has not yet come up for approval in the United States.