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Thursday, January 05, 2006Two new vaccines appear safe and very effective against rotavirus, a major diarrheal killer of young children in poor countries, two huge studies show. The impressive results prompted two government doctors to call for making routine immunization 'a global priority. The first vaccine is an oral vaccine made of live human rotavirus that was altered to make it less infectious and less potent. It's a well-designed study, following equal numbers of vaccine recipients and controls for a ten month period. However, in exploring the adverse effects, they only followed them for 100 days. The vaccine was given in two stages - the first dose at age 6-13 weeks and the booster dose two months later. The good news is that it didn't have the side effect of the old rotavirus vaccine (a mixture of monkey and human rotavirus) that was taken off the market several years ago. That side effect was intussusception. It's success is decidedly mixed, however. The new vaccine did reduce hospitalizations for diarrhea, but not by much - 2.7% of the kids who were vaccinated were hospitalized compared to 3.1% of the controls. There was a greater difference in hospitalization rates in the children followed for the full ten months, but again, not a dramatic one - 0.1% of the vaccine recipients were hospitalized during those ten months compared to 0.7% of the controls. The death rates in the two groups were the same - so the vaccine didn't make much of a dent in the things that count. In addition, there were more cases of pnuemonia in vaccinated children than in controls - 16 vaccine recipients (0.05%) and 6 in the control group (0.02%) - also very small absolute differences, not enough to get anxious about. The second vaccine is a combination of human rotavirus and cow rotavirus. It, too, found no difference in intussusception rates, but it only observed side effects for 42 days, less than half the time the other study devoted to following adverse effects. Over the course of a full rotavirus season, the cow/human vaccine made a more noticeable difference in hospitalization and emergency room visits than the strictly human virus vaccine did. Among vaccinated children, only 0.04% went to the emergency room for rotavirus-related illness compared to 0.6% of the control group. For hospitalizations, it was 0.02% compared to 0.5%. So, it appears that the bovine-human form of the vaccine confers more of a benefit than the strictly human one, though we're talking about large changes in very small numbers. Of course, multiplying those small numbers by the billions of children in the world, results in a large number of children worldwide who could benefit from the vaccine. That is, if they can afford it, and if they live in societies receptive to vaccines. In the developed world, where access to a hospital is easy to come by, those small increments of change may not be worth the cost. posted by Sydney on 1/05/2006 09:13:00 AM 0 comments 0 Comments: |
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