Objective: To determine rates of seroconversion after single vaccination with a novel split virion, inactivated, adjuvanted pandemic H1N1 influenza vaccine (A/California/7/2009) in HIV-1-infected patients (ClinicalTrials.gov Identifier: NCT01017172).
Design: Single center diagnostic study.
Setting: Institutional HIV outpatient department of an urban university clinic.
Participants: Adult HIV-1-infected individuals.
Intervention: Serum samples were taken before and 21 days after vaccination.
Main outcome measures: Antibody titers determined by hemagglutination inhibition assay. Seroconversion to vaccination was defined by either an antibody titer of 1: 10 or less before and of at least 1: 40 after or at least 1: 10 before and at least four-fold increase in antibody titer 21 days after single vaccination.
Results: One hundred and sixty patients (125 men/35 women) were analyzed. Before vaccination, 23 patients (14.4%) had a hemagglutination inhibition assay titer of at least 1: 40. A median of 22 ± 3 days after vaccination, 110 (69%) patients seroconverted. Seroconverters were younger (45.1 ± 10.0 vs. 48.8 ± 11.3 years; P = 0.04), had a higher CD4 cell count (532 ± 227 vs. 475 ± 281 cells/μl; P = 0.03) and were more likely to have received a previous H5N1 vaccination in 2009 (25 vs. 8%; P = 0.02) when compared to nonresponders. No other significant differences were found comparing the two groups (prevaccination hemagglutination inhibition assay titer of ≥1: 40, AIDS, HAART, HIV RNA PCR <50 copies/ml or CD4 nadir, CD4 and CD8 percentage, sex, BMI, chronic hepatitis B or C).
Conclusion: Seroconversion after one dose of a split virion, inactivated, adjuvanted pandemic H1N1 influenza vaccine of HIV-infected patients was 69%. Studies to investigate whether a second dose of the vaccine will increase seroconversion rate are needed.
bInstitute of Medical Virology, Germany
cInstitute of Biostatistics and Mathematical Modeling, Clinic of the Goethe University, Frankfurt, Germany.
Received 12 January, 2010
Revised 1 March, 2010
Accepted 8 March, 2010
Correspondence to Dr Markus Bickel, HIVCENTER, Goethe University Clinic, Frankfurt, Germany. Tel: +49 69 6301 7478; fax: +49 69 6301 84325; e-mail: email@example.com