Effectiveness of an influenza vaccine programme for care home staff to prevent death, morbidity, and health service use among residents: cluster randomised controlled trial.

Abstract

To determine whether vaccination of care home staff against influenza indirectly protects residents. Pair matched cluster randomised controlled trial. Large private chain of UK care homes during the winters of 2003-4 and 2004-5. Nursing home staff (n=1703) and residents (n=2604) in 44 care homes (22 intervention homes and 22 matched control homes). Vaccination offered to staff in intervention homes but not in control homes. The primary outcome was all cause mortality of residents. Secondary outcomes were influenza-like illness and health service use in residents. In 2003-4 vaccine coverage in full time staff was 48.2% (407/884) in intervention homes and 5.9% (51/859) in control homes. In 2004-5 uptake rates were 43.2% (365/844) and 3.5% (28/800). National influenza rates were substantially below average in 2004-5. In the 2003-4 period of influenza activity significant decreases were found in mortality of residents in intervention homes compared with control homes (rate difference -5.0 per 100 residents, 95% confidence interval -7.0 to -2.0) and in influenza-like illness (P=0.004), consultations with general practitioners for influenza-like illness (P=0.008), and admissions to hospital with influenza-like illness (P=0.009). No significant differences were found in 2004-5 or during periods of no influenza activity in 2003-4. Vaccinating care home staff against influenza can prevent deaths, health service use, and influenza-like illness in residents during periods of moderate influenza activity. National Research Register N0530147256.