- Andrew C Hayward, senior lecturer in infectious disease epidemiology1,
- Richard Harling, honorary lecturer1,
- Sally Wetten, research assistant1,
- Anne M Johnson, professor of infectious disease epidemiology1,
- Susan Munro, senior nurse manager2,
- Julia Smedley, honorary senior lecturer3,
- Shahed Murad, statistician1,
- John M Watson, consultant epidemiologist4
- 1University College London Centre for Infectious Disease Epidemiology, Department of Primary Care and Population Sciences, London NW3 2PF
- 2Westminster Healthcare, Leatherhead, Surrey
- 3Medical Research Council Epidemiology Resource Centre, Southampton General Hospital
- 4Health Protection Agency Centre for Infections, London
- Correspondence to: A Hayward
- Accepted 10 October 2006
Objective To determine whether vaccination of care home staff against influenza indirectly protects residents.
Design Pair matched cluster randomised controlled trial.
Setting Large private chain of UK care homes during the winters of 2003-4 and 2004-5.
Participants Nursing home staff (n=1703) and residents (n=2604) in 44 care homes (22 intervention homes and 22 matched control homes).
Interventions Vaccination offered to staff in intervention homes but not in control homes.
Main outcome measures The primary outcome was all cause mortality of residents. Secondary outcomes were influenza-like illness and health service use in residents.
Results 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.
Conclusions Vaccinating care home staff against influenza can prevent deaths, health service use, and influenza-like illness in residents during periods of moderate influenza activity.
Trial registration National Research Register N0530147256.
Forest plots for rate differences during year 1 are on bmj.com
We thank the lead nurses in the care homes who helped to implement the intervention and collect the data.
Contributors: All authors were substantially involved in the conception and design of the study, or analysis and interpretation of data, drafting the article or revising it critically for important intellectual content, and final approval of the version to be published. ACH was the principal investigator and is guarantor.
Funding: Department of Health, which had no role in the collection, analysis, or interpretation of data; the writing of the report; or the decision to submit the paper for publication. ACH is funded by Camden primary care trust.
Competing interests: None declared.
Ethical approval: This study was approved by the London multicentre research ethics committee (No 02/2/56).