All shot up: the flu vaccine controversy

All shot up: the flu vaccine controversy

The hot topic right now is what to do about childhood vaccination against epidemic influenza, following the series of apparent adverse reaction to influenza vaccine in pre-schoolers. Already there has been a lot of heat, plenty of noise but not a lot of light on the issue. It is frustrating for all concerned. Not only for the parents of children who’ve had rash, fever or even a febrile convulsion. It is also frustrating for responsible health professionals who’ve advocated an expanded influenza vaccination programme on the basis of hard-won statistical evidence in order to reduce the risk of influenza complications in the most vulnerable. An early evaluation appeared to indicate that the H1N1/09 specific vaccine would be safe in children, though a more recent report indicated a higher rate of mild to moderate adverse reactions in children. Earlier this year there was an impression that there had been a disappointing uptake of pandemic flu vaccine after the winter epidemic of 2009. This was suprising given the severity of disease in specific adult groups, some of whom required admission to intensive care.

In the few days since this issue first arose a series of possible explanations have been offered for the series of apparent vaccine reactions in paediatric patients. These include an immune memory response in children who had already been exposed during last year’s flu season,  a particular batch of vaccine, vaccine potentiation by a second and possibly unrelated viral infection, an abnormally exaggerated vaccine response, or a combination of more than one of these.

Teasing out the various strands of possible cause and effect is a complicated process under the best of conditions. The nature of the public debate means that the health detective work that needs to proceed urgently and methodically risks being diverted by critics who hold to a more general anti-vaccine agenda. Expert opinion, given with the best of intentions is currently in danger of being used out of context to support an unscientific, 19th century view of vaccination.

Readers of this Blog are reminded that it takes a sizeable body of evidence to pin the blame on a specific microbe as both sufficient and necessary cause of a given disease outcome, even if the microbe has been administered deliberately by needle.

There are four key evidentiary stages to nailing the microbial culprit;

  1. congruence
  2. consistency
  3. cumulative dissonance
  4. curtailment

How these operate can be found in the original paper. In outline, the clinical and pathological features of individual cases, the epidemiology and the molecular biology must add up. But that just get’s you to first base. There must also be consistency, a mechanistic explanation for how the microbe exerts its effects, and finally a demonstration of the effect of one or more specific interventions to curtail the infective process.

Application of this evidence-building exercise to the current alleged vaccine reactions at the present time illustrates (a)  the strength of evidence for a causal relationship, and (b) helps identify priorities for further investigation, without losing sight of the need to continue vaccination of vulnerable adults in groups who have yet to show any adverse effects of the current influenza vaccine.

These comments are subject to the caveat at the bottom of the MicroGnome website’s homepage.


  1. All shot up: the flu vaccine controversy (micrognome)

  2. RT @precordialthump: All shot up: the flu vaccine controversy (micrognome)

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