[afro-nets] Lancet Web Publishes Cochrane Review of Influenza Vaccines

[Dr Tom Jefferson <TOJ1@aol.com>]

Lancet Web Publishes Cochrane Review of Influenza Vaccines in
the Elderly
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Summary

Introduction
Influenza vaccination of the elderly is recommended worldwide.
We synthesised the evidence of efficacy and effectiveness of in-
fluenza vaccines in persons aged 65 or more.

Methods
We searched 5 electronic database to December 2004 in any lan-
guage for randomised, cohort and case-control studies assessing
efficacy against influenza (reduction in laboratory confirmed
cases) and effectiveness against influenza-like illness (reduc-
tion 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, In-
fluenza-like illness, hospital admissions, complications and
deaths.

Findings
In homes for the elderly (with good vaccine match and high viral
circulation) the effectiveness of vaccines against influenza-
like illness was 23% and non significant against influenza.
Well-matched vaccines prevented pneumonia (VE 46%), hospital ad-
missions (VE 45%), deaths from influenza or pneumonia (VE 42%)
and reduced all-cause mortality (VE 60%). In elderly community-
dwellers vaccines were not significantly effective against in-
fluenza, influenza-like illness or pneumonia. Well-matched vac-
cines  prevented hospital admission for influenza and pneumonia
(VE 26%) and all-cause mortality (VE 42%). After adjustment for
confounders vaccine performance was improved for admission to
hospital for influenza or pneumonia (VE* 27%), respiratory dis-
eases (VE* 22), and cardiac disease (VE* 24%) and for all-cause
mortality (VE* 47%).

Interpretation
In long term care facilities where vaccination achieves a
greater effect on the complications the aims of the campaign are
partly met. However, according to reliable evidence the useful-
ness of vaccines in the community is modest.

Jefferson T, Rivetti D,  Rivetti A, Rudin M, Di Pietrantonj C,
Demicheli V. Efficacy and effectiveness of influenza vaccines in
elderly people: systematic review. Lancet 2005; 366:1165 -1174.
www.thelancet.com

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Dr Tom Jefferson
Cochrane Vaccines Field
Via Adige 28a
00061 Anguillara Sabazia
Roma, Italy
Tel/Fax: +39-06-999-00989
Mobile:  +39-32-920-25051
mailto:toj1@aol.com