Influenza vaccine for all?
==========================

* Ross Upshur

*   © 2005 CMA Media Inc. or its licensors

I find it interesting that, a few weeks after celebrating the achievements of the Cochrane Collaboration,1 *CMAJ* published a systematic review2 and a recommendation statement from the Canadian Task Force on Preventive Health Care3 on preventing influenza in the general population (and the authors of the systematic review were quoted in the lay press as endorsing universal vaccination4), when a Cochrane review of the topic5 already exists.

The Cochrane systematic review,5 alluded to but not cited by Joanne Langley and Marie Faughnan,2 concludes that “[i]nfluenza vaccines are effective in reducing serologically confirmed cases of influenza. However, they are not as effective in reducing cases of clinical influenza and number of working days lost. Universal immunisation of healthy adults is not supported by the results of this review.”

Langley and Faughnan2 state that their goal was to determine the efficacy of the vaccine, not the efficacy of a universal vaccination program. Yet it appears that they, and the task force, endorse such a strategy, without evidence related to a variety of ancillary considerations that they identify (including economic costs, vaccine procurement and public acceptability).

Something is missing here. Was the *CMAJ* systematic review not the compelling piece of evidence leading to the task force's endorsement of universal vaccination? Was the conclusion of the Cochrane Collaboration wrong? Is there evidence of cost-effectiveness, and have procurement issues been sorted out? Just how many systematic reviews do we need on a particular topic?

R.A. Fisher, the pioneering methodologist for randomized trials and the most influential statistician of the 20th century,6 envisioned controlled trials (and, by extension, systematic reviews and meta-analyses) as an essential technique to reduce the interpretive variability of study results. I wish he and Archie Cochrane were still around to help us sort this out.

## Footnotes

*   *Competing interests:* None declared.

## References

1.  1. The Cochrane Collaboration at 10: kudos and challenges [editorial]. CMAJ 2004;171(7):701.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czo5OiIxNzEvNy83MDEiO3M6NDoiYXRvbSI7czoyMzoiL2NtYWovMTcyLzkvMTE2MS4yLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

2.  2. Langley JM, Faughnan ME. Prevention of influenza in the general population. CMAJ 2004;171(10):1213-22.
    
    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMToiMTcxLzEwLzEyMTMiO3M6NDoiYXRvbSI7czoyMzoiL2NtYWovMTcyLzkvMTE2MS4yLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

3.  3. Langley JM, Faughnan ME; Canadian Task Force on Preventive Health Care. Prevention of influenza in the general population: recommendation statement from the Canadian Task Force on Preventive Health Care. CMAJ 2004;171(10):1169-70.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMToiMTcxLzEwLzExNjkiO3M6NDoiYXRvbSI7czoyMzoiL2NtYWovMTcyLzkvMTE2MS4yLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

4.  4. Picard A. MDs back flu shots for every Canadian. *The Globe and Mail* [Toronto] 2004 Nov 9; Sect A:1.
    
    

5.  5. Demicheli V, Rivetti D, Deeks JJ, Jefferson TO. Vaccines for preventing influenza in healthy adults. In: The Cochrane Library; Issue 3, 2004. Oxford: Update Software.
    
    

6.  6. R.A. Fisher digital archive. Adelaide, Australia: University of Adelaide Library; 2004.