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JAMA. 1994 Dec 7;272(21):1661-5.

The efficacy of influenza vaccination in elderly individuals. A randomized double-blind placebo-controlled trial.

Author information

1
Department of General Practice, University of Limburg, Maastricht, The Netherlands.

Abstract

OBJECTIVE:

To determine the efficacy of influenza vaccination in elderly people.

DESIGN:

Randomized double-blind placebo-controlled trial.

SETTING:

Fifteen family practices in the Netherlands during influenza season 1991-1992.

PARTICIPANTS:

A total of 1838 subjects aged 60 years or older, not known as belonging to those high-risk groups in which vaccination was previously given.

INTERVENTION:

Purified split-virion vaccine containing A/Singapore/6/86(H1N1), A/Beijing/353/89(H3N2), B/Beijing/1/87, and B/Panama/45/90 (n = 927) or intramuscular placebo containing physiological saline solution (n = 911).

MAIN OUTCOME MEASURES:

Patients presenting with influenzalike illness up to 5 months after vaccination; self-reported influenza in postal questionnaires 10 weeks and 5 months after vaccination; serological influenza (fourfold increase of antibody titer between 3 weeks and 5 months after vaccination).

RESULTS:

The incidence of serological influenza was 4% in the vaccine group and 9% in the placebo group (relative risk [RR], 0.50; 95% confidence interval [CI], 0.35 to 0.61). The incidences of clinical influenza were 2% and 3%, respectively (RR, 0.53; 95% CI, 0.39 to 0.73). The effect was strongest for the combination of serological and clinical influenza (RR, 0.42; 95% CI, 0.23 to 0.74). The effect was less pronounced for self-reported influenza.

CONCLUSION:

In the elderly, influenza vaccination may halve the incidence of serological and clinical influenza (in periods of antigenic drift).

PMID:
7966893
[Indexed for MEDLINE]

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