Epidemiology and Infection

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Epidemiology and Infection (2009), 137:994-1002 Cambridge University Press
Copyright © 2008 Cambridge University Press
doi:10.1017/S0950268808001386

Original Papers

Influenza, Legionnaires' disease and respiratory infections

Effectiveness of influenza vaccination in the elderly in South Africa


A. van VUURENa1a2 c1, P. RHEEDERa2a3 and E. HAKa4

a1 MEDICHRON Division, Medihelp Medical Scheme, Pretoria, South Africa
a2 School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
a3 Division of Clinical Epidemiology, University of Pretoria, Pretoria, South Africa
a4 Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
Article author query
van vuuren a [PubMed]  [Google Scholar]
rheeder p [PubMed]  [Google Scholar]
hak e [PubMed]  [Google Scholar]

SUMMARY

This study primarily aimed to estimate the association between influenza vaccination and the occurrence of hospitalization for acute respiratory or cardiovascular diseases, or all-cause death during the influenza season in an elderly population in South Africa. We conducted a nested case-control study using data from a cohort of 45 522 elderly members of a private medical funding organization during the moderate 2004 influenza season. In 1282 (2·8%) subjects the combined outcome occurred and the influenza vaccination rate in controls was 15·4%. After adjustments for measured confounders, vaccination was associated with a statistically significant reduction of 19% (95% confidence interval 3·1–32·9) in the combined outcome. Post-hoc sensitivity analysis of the potential impact of potential healthy user bias showed that confounding, if present, could have caused this finding. Our data were inconclusive regarding the benefits of influenza vaccination in elderly persons in South Africa and given the low vaccine uptake, long-term follow-up is warranted.

(Accepted September 01 2008)

(Online publication October 17 2008)

Key Words:Elderly; influenza; nested case-control; South Africa; vaccination

Correspondence:

c1 Author for correspondence: A. van Vuuren, Medihelp, PO Box 26004, Arcadia, 0007, South Africa. (Email: avanvuuren@medihelp.co.za)


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