To Vaccinate or Not To Vaccinate

Does the flu vaccine do any good?  In our November magazine, Shannon Brownlee and Jeane Lenzer suggested that the apparent beneficial effect might be due more to selection bias than to any actual impact of the injection:  people who get a flu shot are probably more conscientious about their health in many areas, which messes up your numbers.  The core problem seems to be that, unlike childhood illnesses, the groups most at risk from dying of flu, and therefore the most likely to be vaccinated, are often also the groups least likely to mount a good immune response to the vaccine--after all, the reason they're at risk is, in most cases, that their immune system can't take care of business. 

A science-loving friend sent the article to his brother, a public health researcher at a major university, and passes the commentary on to me:

I think there is a responsible debate about the benefits of population-wide influenza immunization (as opposed to the kooky fringe opponents to all childhood vaccinations)

Mainly it is a one of magnitude. mostly the debate concerns the ubiquitous phenomenon of more netbenefit accruing when you target higher risk groups. The more broadly a population vaccination program is, the smaller the net benefit. Likewise, the net benefit varies with how well the yearly vaccine matches the actual infecting strains. The latter may dramatically improve with some of the technology developed as part of producing this years H1N1 vaccine allowing them to choose the virus cocktail later.

And like the (especially) breast and prostate screening controversies, part of the debate is over whether one should confuse the public by airing the debate in public lest you scare off the high risk people who almost everyone would agree should get vaccinated/screened.

Some unknowns (or not well defined) things that affect recs about vaccination strategies:

1) the role of "herd immunity" - so broader vaccination in groups that don't directly benefit may, by breaking up transmission, benefit the high risk groups especially given:

2) the uncertain clinical significance of the diminished vaccine response in the high risk groups (older/sicker people don't make as many antibodies after vaccination but may still get substantial benefit) and this year

3) the fact that the current pandemic(with its risk of mutation and dramatic worsening) may overwhelm capacity makes any benefit from vaccination potentially worth going for as each increment in influenza illness burden could represent the straw that breaks the camels back from the point of view of health care capacity or even economic activity.

As you can imagine, lots of good modeling opportunities here to explore the impact of different levels of the unknowns.

I'm supposed to get a flu shot, because I have asthma, and flu usually turns into horrendous bronchitis.  But I may reconsider.