Methods: We conducted a prospective cohort study evaluating the immunogenicity of monovalent influenza A (H1N1) vaccination among HIV+ and HIV- adults (18-50 years of age) during the 2009-2010 influenza season. Antibody titers were evaluated at baseline, day 28, and 6 months post-vaccination using hemagluttination inhibition assays. Serum 25(OH)D levels were measured at day 28. Univariate and multivariate regression analyses examined the association between 25(OH)D levels [categorized as <20 ng (deficiency) vs. >20 ng] with the primary outcome of post-vaccination seroconversion. Secondary outcomes included seroprotection; a ≥4-fold increase in titers; and GMTs post-vaccination. Analyses were repeated evaluating the 25(OH)D level as a continuous variable.
Results: A total of 128 adults (64 HIV+ and 64 HIV-) were included. HIV+ had a median CD4 count 580 cells/mm3. Seroconversion at day 28 post-vaccination was achieved in fewer HIV+ compared with HIV- participants (56% vs. 74%, p=0.03). Similarly, HIV+ persons had lower GMTs at day 28 (269 vs. 80, p=0.003) and 6 months (113 vs. 20, p=0.0002) post-vaccination. Vitamin D deficiency was more prevalent among HIV+ vs. HIV- persons (25% vs. 17%), although not significantly different (p=0.39). There were no associations found between lower 25(OH)D levels and poorer antibody responses at day 28 or month 6 post-vaccination for any of the study outcomes among either HIV+ or HIV- adults.
Conclusion: Vitamin D deficiency was common among both HIV+ and HIV- adults, but lower levels did not predict antibody responses after H1N1 (2009) influenza vaccination. Low 25(OH)D levels do not explain the poorer post-influenza vaccination responses among HIV+ persons. Further research is needed to improve vaccine immunogenicity especially among HIV+ persons.
R. Lee, None
T. Lalani, None
A. Ganesan, None
T. Burgess, None
B. Agan, None