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New Vaccine Against Rotavirus Approved

Posted on: Saturday, 4 February 2006, 09:00 CST

By Justin Gillis, Washington Post Staff Writer

A new vaccine against one of the most common ailments of childhood won federal approval yesterday, six years after a similar vaccine was pulled from the market for injuring scores of babies.

The vaccine is designed to prevent serious illness from rotavirus, an intestinal germ that sickens many babies in the United States and kills hundreds of thousands overseas every year. Federal experts are expected to recommend, possibly before the month is out, that it be given to all infants, a step that could prevent 50,000 hospitalizations a year in the United States and save the nation more than $1 billion in health care costs and missed work for parents.

But vaccine-safety advocates are already warning parents to be cautious, citing the problems with the earlier vaccine, known as RotaShield. Over the next couple of years, with relatively little known about the vaccine in real-world use, parents of the roughly 4 million American babies born each year will have to decide whether to allow doctors to administer it to their children.

The new vaccine will be sold by Merck & Co. of Whitehouse Station, N.J., under the brand name RotaTeq. Merck, at the direction of the Food and Drug Administration, conducted a test of RotaTeq involving 68,038 babies in 11 countries. GlaxoSmithKline PLC of London, developing a similar vaccine that has not yet been licensed in the United States, conducted a test nearly as large as Merck's in 12 countries.

Those two tests are the largest vaccine trials ever conducted by drug companies, and the largest by any sponsor since the March of Dimes trials in the 1950s that led to the eradication of polio in the Western world. Both tests showed the vaccines to be safe and effective, and doctors said they had largely ruled out the prospect that the new vaccines could cause a reaction similar to the one that felled RotaShield in 1999.

RotaShield caused a serious intestinal problem called intussusception, a type of bowel obstruction that occurs when the intestine folds in on itself, like a collapsing telescope. The problem occurs naturally, albeit rarely; it showed up at a sharply elevated rate in babies that received RotaShield. Intussusception is life-threatening for some babies, though doctors can usually treat it.

In Merck's test, published last month in the New England Journal of Medicine, the babies were divided into two groups of more than 34,000 each, with one group getting the vaccine -- a drop of liquid placed in the cheek -- and the other getting a dummy vaccine. Nurses and doctors in the study didn't know which baby got what.

In the vaccine group, 12 babies got the intestinal blockage, while in the placebo group, 15 babies got it. Doctors think the difference is due to chance, and they take the figures as strong evidence that RotaTeq does not elevate the risk of intussusception. Moreover, it prevented 98 percent of serious rotavirus disease in babies during their first year, an effectiveness level rarely seen in any vaccine.

"I'm excited about the vaccine," said Penelope Dennehy, a Brown University doctor in Providence, R.I., who treats serious infectious disease and helped test RotaTeq. "This is a huge study compared with most studies. The vaccine and the placebo groups look so close -- we're not seeing the signals we saw with the other vaccine."

But Melynda Slay, a computer programmer in Raleigh, urged parents to do their homework before agreeing to the new vaccine.

Her son, Harrison, was administered RotaShield when he was born in 1999, and developed a severe reaction. Doctors dismissed her concerns for days, she said. Severely dehydrated, the child was eventually hospitalized, diagnosed with intussusception and treated successfully, though he suffered after-effects for years, she said.

The experience made her more cautious -- she has gotten most of the recommended vaccines for Harrison, but only after careful study, and she has refused some newer vaccines until more is known about them. She said the medical profession does a poor job of alerting parents to potential side effects, and she urged parents to find and read for themselves the detailed FDA disclosures that will be issued regarding RotaTeq.

Paul A. Offit, a pediatrician at Children's Hospital of Philadelphia who helped invent RotaTeq, said that parents who refuse the vaccine will be putting their babies at risk of a serious disease that is now preventable. "The question becomes, which is the conservative and which is the radical decision?" he said. "I think the more radical choice, frankly, is not to give the vaccine."

FDA administrators said they had requested an "extremely aggressive" safety monitoring program after the vaccine hits the market, with Merck committing to study 44,000 children and additional studies planned by the Centers for Disease Control and Prevention. "I think we have a lot of data here that are reassuring," said Jesse L. Goodman, director of biologics evaluation and research at the FDA, while acknowledging that the data "are not conclusive."

Virtually every child in the world contracts it repeatedly by age 5, and the first episode is generally the worst, with simultaneous vomiting and diarrhea. Occasionally, the babies can become severely dehydrated, a life-threatening condition.

RotaTeq and its forthcoming competitor, Rotarix, contain several live, but weakened, strains of rotavirus that are designed to build a child's immunity without inducing illness. RotaShield was made in a similar way, but the strains in the newer vaccines are different and appear less likely to cause problems than did the ones in RotaShield.

Federal authorities are expected to recommend three doses of RotaTeq on the normal infant vaccination schedule, at two, four and six months of age. The vaccine wasn't tested in older children and is unlikely to be recommended for them, at least not right away.

While 50,000 or so American children are hospitalized every year with severe rotavirus infections, U.S. doctors typically can save all but 50 or 60 of them. But many babies die in poor countries, where health care systems are much weaker. Both Merck and GlaxoSmithKline say they are committed to supplying their vaccines to poor countries at reduced prices.

Reported By TechNews.com, http://www.TechNews.com

(20060204/WIRES /)

Source: Newsbytes

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