Rates of seroprotection and geometric mean titer increases after seasonal influenza vaccination are similar across age groups in HIV-infected adults in the HAART era
M. Kitchen1, O. Kistner2, W. Wodal2, M. Gisinger1, M. Sarcletti1, R. Zangerle1
1Medical University Innsbruck, Innsbruck, Austria, 2Biomedical Research Center, Orth, Austria
Background: Vaccination against saisonal influenza is recommended for all HIV-infected persons. Data are limited on vaccine efficacy in the HAART era and have not been reported for elderly patients. We investigated seroprotection rates (SP) and geometric mean titers (GMT) in HIV infected adults and compared rates between different age groups.
Methods: Plasma samples of 346 vaccinees were analysed for anti-haemagglutinin antibody against the egg-derived influenza virus wild type strains A/Brisbane/59/2007 (A/H1N1), A/Uruguay/716/2007 (A/H3N2), and B/Florida/4/2006 (B) by haemagglutination inhibition assay pre and post influenza vaccination in autumn 2008.
Results: 69% of patients were male, the median age was 45 years. 403 individuals (88%) had a viral load < 400 copies/ml. The median CD4 count was 598/µl.
[Seroprotection before/after influenza vaccination]
| ||Age (years)||Up to 30
59/2007||SP pre vacc.||91.2%||97.8%||95.7%||97.1%||96.2%|
| ||post vacc||100.0%||99.3%||97.2%||100.0%||98.6%|
| ||GMT increase||2.6||2.1||2.1||2.1||2.2|
716/2007||SP pre vacc.||23.5%||33.1%||54.6%||52.9%||42.8%|
| ||post vacc||50.0%||73.7%||84.4%||85.3%||76.7%|
| ||GMT increase||3.4||3.2||3.7||3.4||3.4|
4/2006||SP pre vacc.||97.1%||99.3%||96.5%||100.0%||98.0%|
| ||post vacc||100.0%||99.3%||99.3%||100.0%||99.4%|
| ||GMT increase||2.0||1.7||1.8||1.6||1.8|
Conclusions: Before influenza vaccination 2008 seroprotection rates were already very high for both A/H1N1 and B without differences between the age groups. Pre-vaccination seroprotection rates for the A/H3N2 strain were low in young adults and remained lower after vaccination. Our data suggest that responses to influenza vaccination in elderly HIV infected individuals are not inferior to the responses seen in younger adults, at least for the influenza season 2008/09.
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