Where’s the evidence for flu vaccination?
Although vaccination of healthcare workers against influenza is ‘widely recommended', I'm not aware of a single study that has assessed if and to what extent immunisation of healthcare workers protects either patients or workers themselves from flu.
Actually, we are still not sure about the impact the last flu vaccination, for swine flu, may have had on patients, or about its cost-effectiveness.
A 2006 Cochrane review of flu vaccination in the elderly stated: ‘The apparent high effectiveness of the vaccines in preventing death from all causes may reflect a baseline imbalance in health status and other systematic differences in the two groups of participants.' A study on selection bias for flu vaccine in the elderly found it could account for the entirety of the protective effect.
A 2007 Cochrane review on flu vaccines in healthy adults found that while vaccines were effective against the strains they are designed to vaccinate against, this ended up translating to only a modest impact on working days lost due to infection.
On the other hand, as anyone knows, side-effects include mild soreness, redness and swelling, fever, aches, runny nose or nasal congestion, cough, chills, weakness, tiredness, headache, and – rarely – a life-threatening allergic reaction. The few studies demonstrating benefit from staff vaccination were performed in long-term care institutions, not in primary care clinics, and are methodologically flawed. Further evidence is needed.
From Dr Edoardo Cervoni