Meta-analyses of flu vaccine effectiveness/ Cochrane Collaboration

The Cochrane Collaboration, the most respected organization of health professionals to evaluate the evidence behind medical therapies, studied flu vaccine of healthcare workers in 2006 and again in 2010.

In 2006 they concluded:

There is evidence that vaccinating the elderly has a modest impact on the complications from influenza. There is also high quality evidence that vaccinating healthy adults under 60 (which includes healthcare workers) reduces cases of influenza. Both the elderly in institutions and the healthcare workers who care for them could be vaccinated for their own protection, but an incremental benefit of vaccinating healthcare workers for the benefit of the elderly cannot be proven without better studies.

NO evidence supports the wholesale vaccination of healthcare workers to protect patients. 

In 2010 Cochrane concluded:

Influenza vaccination for healthcare workers who work with the elderly 

Authors' conclusions

No effect was shown for specific outcomes: laboratory-proven influenza, pneumonia and death from pneumonia. An effect was shown for the non-specific outcomes of ILI, GP consultations for ILI and all-cause mortality in individuals ≥ 60. These non-specific outcomes are difficult to interpret because ILI includes many pathogens, and winter influenza contributes < 10% to all-cause mortality in individuals ≥ 60. The key interest is preventing laboratory-proven influenza in individuals ≥ 60, pneumonia and deaths from pneumonia, and we cannot draw such conclusions. 

There are no accurate data on rates of laboratory-proven influenza in healthcare workers. 

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. 

The studies found that vaccinating healthcare workers who look after the elderly in long-term care facilities did not show any effect on the specific outcomes of interest, namely laboratory-proven influenza, pneumonia or deaths from pneumonia. An effect was shown for outcomes with a non-specific relationship to influenza, namely influenza-like illness (which includes many other viruses and bacteria than influenza), GP consultations for influenza-like illness, hospital admissions and the overall mortality of the elderly (winter influenza is responsible for less than 10% of the deaths of individuals over 60 and overall mortality thus reflects many other causes). 

Healthcare workers have lower rates of influenza vaccination than the elderly and surveys show that healthcare workers who do not get vaccinated do not perceive themselves at risk, doubt the efficacy of influenza vaccine, have concerns about side effects, and some do not perceive their patients to be at risk. This review did not find information on other interventions that can be used in conjunction with vaccinating healthcare workers, for example hand washing, face masks, early detection of laboratory-proven influenza in individuals with influenza-like illness by using nasal swabs, quarantine of floors and entire long-term care facilities during outbreaks, avoiding new admissions, prompt use of anti-virals, and asking healthcare workers with an influenza-like illness not to present for work. 

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. Other interventions such as hand washing, masks, early detection of influenza with nasal swabs, anti-virals, quarantine, restricting visitors and asking healthcare workers with an influenza-like illness not to attend work might protect individuals over 60 in long-term care facilities and high quality randomised controlled trials testing combinations of these interventions are needed.