Outbreak of influenza A in an Ontario nursing home - January 1997

Programme de formation en épidémiologie d'intervention, LLCM, Ottawa.
Canada communicable disease report = Relevé des maladies transmissibles au Canada 08/1997; 23(14):105-8.
Source: PubMed
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    ABSTRACT: Influenza vaccination of elderly individuals is recommended worldwide. Our aim was to review the evidence of efficacy and effectiveness of influenza vaccines in individuals aged 65 years or older. We searched five electronic databases to December, 2004, in any language, for randomised (n=5), cohort (n=49), and case-control (n=10) studies, assessing efficacy against influenza (reduction in laboratory-confirmed cases) or effectiveness against influenza-like illness (reduction in symptomatic cases). We expressed vaccine efficacy or effectiveness as a proportion, using the formula VE=1-relative risk (RR) or VE*=1-odds ratio (OR). We analysed the following outcomes: influenza, influenza-like illness, hospital admissions, complications, and deaths. In homes for elderly individuals (with good vaccine match and high viral circulation) the effectiveness of vaccines against influenza-like illness was 23% (95% CI 6-36) and non-significant against influenza (RR 1.04, 0.43-2.51). Well matched vaccines prevented pneumonia (VE 46%, 30-58) and hospital admission (VE 45%, 16-64) for and deaths from influenza or pneumonia (VE 42%, 17-59), and reduced all-cause mortality (VE 60%, 23-79). In elderly individuals living in the community, vaccines were not significantly effective against influenza (RR 0.19, 0.02-2.01), influenza-like illness (RR 1.05, 0.58-1.89), or pneumonia (RR 0.88, 0.64-1.20). Well matched vaccines prevented hospital admission for influenza and pneumonia (VE 26%, 12-38) and all-cause mortality (VE 42%, 24-55). After adjustment for confounders, vaccine performance was improved for admissions to hospital for influenza or pneumonia (VE* 27%, 21-33), respiratory diseases (VE* 22%, 15-28), and cardiac disease (VE* 24%, 18-30), and for all-cause mortality (VE* 47%, 39-54). In long-term care facilities, where vaccination is most effective against complications, the aims of the vaccination campaign are fulfilled, at least in part. However, according to reliable evidence the usefulness of vaccines in the community is modest.
    The Lancet 11/2005; 366(9492):1165-74. DOI:10.1016/S0140-6736(05)67339-4 · 45.22 Impact Factor
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    ABSTRACT: Influenza vaccination of elderly individuals is recommended worldwide as people aged 65 and older are at highest risk for complications, hospitalisations and deaths from influenza. The review looked at evidence from experimental and non-experimental studies carried out over 40 years of influenza vaccination. Seventy-one studies were included and were grouped first according to study design and then to setting (community or long-term care facilities). The results of the review are mostly based on non-experimental (observational) studies, which are at greater risk of bias, as not many good quality trials were available. Trivalent inactivated are the most commonly used influenza vaccines. Best effectiveness of current vaccines in preventing clinical illness and its complications was seen in long-term care facilities (for example nursing homes) where vaccines prevented about 45% of pneumonia cases, hospital admissions and influenza-related deaths. This compared to about 25% vaccine efficacy in preventing hospitalisation from influenza or respiratory illness in open community settings. The public health safety profile of the vaccines appears to be acceptable.
    Cochrane database of systematic reviews (Online) 02/2006; 3(3):CD004876. DOI:10.1002/14651858.CD004876.pub2 · 6.03 Impact Factor
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    ABSTRACT: 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.
    Cochrane database of systematic reviews (Online) 02/2006; 3(3):CD005187. DOI:10.1002/14651858.CD005187.pub2 · 6.03 Impact Factor
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