Influenza vaccination of health care workers
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* Peter Doshi
* Elia Abi-Jaoude
* Joel Lexchin
* Tom Jefferson
* Roger E. Thomas

To support his argument in favour of compulsory influenza vaccination of health care workers, Flegel1 cites a Cochrane review2 as evidence of the vaccine’s benefit.

However the following points should be noted:

*   Flegel fails to convey to readers the Cochrane review’s warning: “All findings must be interpreted with caution given the presence of selection bias.”2

*   The author has cited the 2006 version of the Cochrane review,2 rather than the up-to-date version from 2010.3

*   The up-to-date Cochrane review from 2010 largely contradicts Flegel’s statements, and suggests the evidence of benefit is poor. The reviewers write: “The three studies in the first publication of this review and the two new studies we identified in this update are all at high risk of bias.” They summarize: “We conclude that there is no evidence that only vaccinating healthcare workers prevents laboratory-proven influenza, pneumonia, and death from pneumonia in elderly residents in long-term care facilities.”

*   Flegel also failed to cite another Cochrane review, which suggests alternatives to vaccination: “Implementing barriers to transmission, such as isolation, and hygienic measures (wearing masks, gloves and gowns) can be effective in containing respiratory virus epidemics or in hospital wards.”4 These issues should be clarified and corrected.

![Figure1](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/185/2/150.1/F1.medium.gif)

[Figure1](http://www.cmaj.ca/content/185/2/150.1/F1)

Image courtesy of © 2013 Thinkstock

## References

1.  Flegel K. Health care workers must protect patients from influenza by taking the annual vaccine. CMAJ 2012;184:1873.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMToiMTg0LzE3LzE4NzMiO3M6NDoiYXRvbSI7czoyMjoiL2NtYWovMTg1LzIvMTUwLjEuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

2.  Thomas RE, Jefferson T, Demicheli V, et al. Influenza vaccination for healthcare workers who work with the elderly [review]. Cochrane Database Syst Rev 2006;(3):CD005187.
    
    

3.  Thomas RE, Jefferson T, Lasserson TJ. Influenza vaccination for healthcare workers who work with the elderly. Cochrane Database Syst Rev [review] 2010;(2):CD005187.
    
    

4.  Jefferson T, Del Mar C, Dooley L, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses [review]. Cochrane Database Syst Rev 2010;(1):CD006207.