Posted by When it comes to vaccinations, a high degree of safety is one of the paramount issues. This is because even a small risk, like one in a million, when multiplied by tens of millions will produce tens or more of adverse events. The trade-off, of course, is the prevention of the disease the vaccine is directed against. Unlike a therapeutic drug, when a vaccine works, nothing happens. When there is a side effect, a previously well person becomes sick from the vaccine itself. This becomes a tricky problem in public health education. The recent scare in Israel with influenza vaccine illustrates what can happen. The Israelis are now saying the sudden deaths within days of vaccination in high risk elderly was not due to the vaccine, but that is both difficult to demonstrate conclusively and sometimes not persuasive to people, whatever the truth of the matter. After all, there is a clear temporal relationship between the vaccination and the event in their eyes which has a great deal of cogency.
Vaccinating children has all these problems and more. Concern about the next generation is probably hardwired into our behavior (it is evoloutionarily advantageous), so emotions run even higher. The publicity over autism and measles-mumps-rubella (MMR) vaccinations is a case in point. MMR and many other vaccines have a mercury-based preservative in them when packaged in multiple doses. Since mercury in some forms is a known neurotoxin, the thought that the mysterious affliction of autism might be related to this ubiquitous childhood exposure was plausible and interesting and a study or two seem to indicate such a relationship. But intense focus on possibility has shown that this is not a cause of autism after all (we have consulted some of the world’s top autism and mercury experts whose expertise and concern for children’s health we have a great deal of confidence in), but the damage to childhood vaccination programs has been severe. The recent outbreak of mumps in the US has been blamed on an index case imported from the UK, where vaccination rates dropped following the autism scare.
Children, like adults, are a risk for severe complications of influenza, so vaccinating them is an important public health measure. CDC estimates around 90 under 5 year old children die yearly of influenza and many more become seriously ill. Even when they don’t become severely ill, circulation of the virus in school age children may be one of the important drivers for influenza in adults. As influenza season is upon us once again and the threat of a pandemic looms, CDC reports the largest study of side effects in babies and toddlers.
Researchers studied 45,000 U.S. children and found almost no side effects requiring medical treatment during the six weeks after the youngsters were vaccinated.
[snip]
Researchers found a few more cases of mild nausea and diarrhea than expected within the first two weeks after the shot, but the numbers were extremely low considering the thousands of children studied: 13 cases.
After their flu shots, the children were less likely to get treated for upper respiratory tract and ear infections. That could have been because parents felt reassured that the symptoms were not signs of flu, said study co-author Dr. Simon Hambidge, an investigator at Kaiser Permanente Colorado’s clinical research unit. (AP)
The paper is in the current issue of the Journal of the American Medical Association (subscription only). About half of the 19 authors reported some financial ties with vaccine makers. The senior author works for a large HMO (Kaiser Permanente). Since their stake is in seeing reduced morbidity, we think bias against finding side effects is unlikely.
This is a data point in the risk benefit equation for childhood immunization. It tips to the benefit side.
October 26, 2006
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