Journal Article - A Flu Vaccine Study

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The effect of giving influenza vaccination to general practitioners: a

controlled trial [NCT00221676]

Barbara Michiels , Hilde Philips , Coenen , Fernande Yane , Toon

Steinhauser , Sofie Stuyck , Joke Denekens and Van Royen

BMC Medicine 2006, 4:17 doi:10.1186/1741-7015-4-17

http://www.biomedcentral.com/1741-7015/4/17/abstract

Published 10 July 2006

Abstract (provisional)

The complete article is available as a provisional PDF. The fully

formatted PDF and HTML versions are in production.

Background

No efficacy studies of influenza vaccination given to GPs have yet been

published. Therefore, our purpose was to assess the effect of an

inactivated influenza vaccine given to GPs on the rate of clinical

respiratory tract infections (RTIs) and proven influenza cases

(influenza

positive nose and throat swabs and a 4-fold titre rise), while

adjusting

for important covariates.

Methods

In a controlled trial during two consecutive winter periods (2002-2003

and

2003-2004) we compared (77 and 100) vaccinated with (45 and 40)

unvaccinated GPs working in Flanders, Belgium. Influenza antibodies

were

measured immediately prior to and 3-5 weeks after vaccination, as well

as

after the influenza epidemic. During the influenza epidemic, GPs had to

record their contact with influenza cases and their own RTI symptoms

every

day. If they became ill, the GPs had to take nose and throat swabs

during

the first 4 days. We performed a multivariate regression analysis for

covariates using Generalized Estimating Equations.

Results

One half of the GPs (vaccinated or not) developed an RTI during the 2

influenza epidemics. During the two influenza periods, 8.6% of the

vaccinated and 14.7% of the unvaccinated GPs had positive swabs for

influenza (RR: 0.59; 95%CI: 0.28 - 1.24). Multivariate analysis

revealed

that influenza vaccination prevented RTIs and swab-positive influenza

only

among young GPs (ORadj: 0.35; 95%CI: 0.13 - 0.96 and 0.1; 0.01 - 0.75

respectively for 30-year-old GPs). Independent of vaccination, a low

basic

antibody titre against influenza (ORadj 0.57; 95%CI: 0.37 - 0.89) and

the

presence of influenza cases in the family (ORadj 9.24; 95%CI: 2.91 -

29)

were highly predictive of an episode of swab-positive influenza.

Conclusion

Influenza vaccination was shown to protect against proven influenza

among

young GPs. GPs, vaccinated or not, who are very vulnerable to influenza

are those who have a low basic immunity against influenza and, in

particular, those who have family members who develop influenza.