Influenza vaccination for healthcare workers who work with the elderly.

BACKGROUND: Healthcare workers (HCW) (nurses, doctors, other health professionals, cleaners and porters), have substantial rates of clinical and sub-clinical influenza during influenza seasons and may transmit influenza to those in their care, especially the vulnerable elderly. OBJECTIVES: To identify and summarise comparative studies assessing the effects of vaccinating healthcare workers (HCW) on the incidence of influenza, influenza-like-illness (ILI) and its complications on elderly residents in long-term facilities. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Database of Systematic Reviews and the NHS Database of Abstracts of Reviews of Effectiveness (DARE) (The Cochrane Library Issue 1, 2006); MEDLINE (January 1966 to Week 1, February 2006); EMBASE (1974 to March 2006); Biological Abstracts (1969 to December 2004); and Science Citation Index-Expanded (1974 to March 2006). SELECTION CRITERIA: Comparative randomised and non-randomised studies reporting the effects of influenza vaccines on the incidence of viral infections in institutions for the elderly of any type, in any schedule of vaccination given to HCW caring for elderly residents of long-term facilities aged 60 years or older. DATA COLLECTION AND ANALYSIS: Two authors independently extracted data and assessed the methodological quality using criteria from the Cochrane Reviewers' Handbook and the Newcastle-Ottawa scale (for non-randomised studies). MAIN RESULTS: We included two cluster randomised controlled trials (C-RCT) and one cohort study. Staff vaccination appears to have significant effect against ILI (absolute vaccine efficacy (VE) 86%, 95% confidence interval (CI) 40% to 97%) only when patients are vaccinated too; if patients are not vaccinated, staff immunisation shows no effect (based on one C-RCT). Based on a small number of observations from two C-RCTs, the vaccines have no efficacy against influenza (odds ratio (OR) 0.86, 95% CI 0.44 to 1.68) or lower respiratory tract infections (OR 0.70, 95% CI 0.41 to 1.20) but were effective against deaths from pneumonia (VE 39%, 95% CI 2% to 62%) and deaths from all causes (VE 40%, 95% CI 27% to 50%). All findings must be interpreted with caution given the presence of selection bias. AUTHORS' CONCLUSIONS: We concluded that there is no credible evidence that vaccination of healthy people under the age of 60, who are HCWs caring for the elderly, affects influenza complications in those cared for. However, as vaccinating the elderly in institutions reduces the complications of influenza and vaccinating healthy persons under 60 reduces cases of influenza, those with the responsibility of caring for the elderly in institutions may want to increase vaccine coverage and assess its effects in well-designed studies.