Home and Community Care Digest

Home and Community Care Digest 6(1) January 2007 : 0-0

How effective are vaccines at preventing influenza in the elderly?


The goal of the influenza vaccination is to reduce the cases of influenza and its complications among people over 65 years old. This study reviews past literature to determine the effects of the influenza vaccine in the elderly. The findings suggest that virus-matching vaccines are effective at preventing influenza and its complications (e.g., pneumonia and death) among the institutionalized elderly. The results provide some evidence to justify government-funded elderly influenza vaccination programs, such as the one currently in Ontario.
Background: In the past 40 years, vaccinations have been globally adopted as the primary measure to prevent influenza and its complications in the elderly population. Nevertheless, there has been a lack of evidence supporting the appropriate use and effectiveness of influenza vaccinations in the elderly. This study investigates the effects of influenza vaccinations in the elderly aged 65 and above. The possible side-effects of influenza vaccinations are also assessed.

Methods: Sixty-four studies with adults older than 65 years old were included in the assessment of the effects of vaccinations of the elderly. Data were analyzed after studies were categorized according to the setting of the study (i.e., long-term care facilities and the community), level of viral circulation and the vaccine-virus match. Analyses were conducted to eliminate the influence of external variables (e.g., age). The effects of the influenza vaccination were described by the ability to reduce cases of influenza, influenza-like-illnesses (e.g., coughing), influenza-related hospitalization and death.

More specifically, seven of the 64 selected studies were reviewed as they included information from which safety of the influenza vaccinations could be assessed. In this study safety was calculated by the absence of local and systematic side- effects after the vaccinations.

Findings: In long-term care facilities, vaccines that match with the viral strains of influenza (i.e., wellmatched vaccines) were found to be the most effective during influenza outbreaks. Well matched vaccines had a preventive effect against 42% of deaths due to influenza or pneumonia. Its effectiveness in preventing influenza- or pneumonia-related hospitalization was 45% during outbreaks, and 68% during periods of low viral circulation. Its effect in preventing pneumonia was 46%.

Among community-dwelling elderly, well-matched vaccines were effective at preventing hospitalization due to influenza or pneumonia. After the influence of external factors (e.g., age) were eliminated, vaccinations were found to be effective at preventing 22% of respiratory diseases, 24% of cardiac diseases, and 26% of influenza- or pneumonia-related hospitalizations. Vaccination against influenza was not found to be as effective among community-dwelling elderly. The authors concluded that the uptake of vaccines is linked to factors such as socio-economical status and health conditions, which in turn influences the measurement of the effects of vaccines.

Among all the reviewed studies, no side-effects (e.g., fever and depression) were found to be associated with the influenza vaccine. The authors concluded that the vaccines are safe to be used.

Conclusions: In general, the influenza vaccines appear to be safe as no local and systemic side effects were identified. Particularly, vaccines that match the influenza viral strains are most effective at preventing influenza complications in long-term care facilities. To further reduce viral transmission, vaccinating the service providers in the long-term care facilities is also suggested.

Reference: Rivetti, D., Jefferson, T., Thomas, R., Rudin, M., Rivetti, A., Di, Pietrantonj, C., Demicheli, V. "Vaccines for preventing influenza in elderly." Cochrane Database of Systematic Reviews 2006, Issue 3.


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