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Trials, and tribulations, of a rotavirus vaccine

Rotavirus infection, which kills about half a million kids every year (almost all of them in the Third World), is preventable. But the chief mode of protection - a vaccine against it -has traveled a tortuous development route.

Harry Greenberg, MD, has published more than 400 peer-reviewed journal articles, most of them on rotavirus. He was the lead inventor of a rotavirus vaccine, licensed in 1998, that while extremely effective was associated with a rare but serious side effect: an intestinal blockage called intussusception. In 1999 the vaccine was withdrawn from the market.

In the seven or eight years that transpired before the licensing of two second-generation vaccines, an estimated several hundred thousand babies who would have lived if they'd received the shot, died.

This week the New England Journal of Medicine published results of a large-scale study that showed, first, that one of the new vaccines also carries an intussusception risk, albeit a very small one; and, second, that this risk is dwarfed many orders of magnitude over by its benefits, especially in less developed countries. An accompanying commentary Greenberg has written at the Journal's request appears in the same issue.

As Greenberg puts it in a Q&A I conducted for Inside Stanford Medicine:

There are no free lunches. Do you have any idea how many people aspirin kills a year? A lot! But it sure makes headaches better.

In short, assessing the risks of a medical intervention in the absence of a parallel assessment of its benefits makes is senseless.

So is assessing short-term risks without considering long-term ones. As Greenberg notes, a growing body of evidence suggesting that not only the new vaccines but the virus itself induce intussusception, so that over the long haul not getting the vaccine may ultimately put an infant at a greater risk of this outcome than those given either the new vaccines or the old one.

Photo by CDC and is a U.S. Government Work

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