P26.03
Background: Biological or behavioral factors may impact vaccine immunogenicity and efficacy. We investigated the relationship between trial volunteer baseline demographic and behavioral factors and vaccine-specific immune responses in 3 phase I HIV vaccine clinical trials.
Methods: Volunteers at low-risk for HIV infection received 2-4 injections of candidate HIV vaccines over 3 to 6 months in 3 phase I HIV vaccine clinical trials in Kenya, Uganda, Rwanda, Zambia, South Africa and the US from 2010–2013. Vaccine recipients in trial arms with robust IFN-g ELISPOT responses at 4 weeks after the last vaccination were included in the analysis. Multivariate logistic regression model with backward selection was used to assess the relationship between parameters at baseline (gender, age, body mass index (BMI), alcohol use, drug use) and the odds of a positive IFN-g ELISPOT, defined as>38 spot forming cells/ml and>4 fold mean background.
Results: 284 volunteers receiving at least one vaccine dose were included in the analysis. Of these, 44% were female, 54%≤age 26, mean BMI 23.1 (range 14–48). 13% reported weekly or daily alcohol use. Self-reported drug use was rare. Overweight BMI (≥30) correlated with 78% decreased odds of a positive ELISPOT response, p<0.005 When analyzed as a continuous variable, one unit increase in BMI correlated to a 8% decrease in the odds of a positive ELISPOT response, p<0.001. Daily or weekly alcohol use, compared to no alcohol use correlated with 3-fold increase in the odds of positive ELISPOT responses (p<0.05). Age, gender, and any drug use were not associated with ELISPOT responses.
Conclusions: Overweight BMI appears to be associated with decreased immune response to certain HIV vaccine candidates when measured by IFN-g ELISPOT in healthy, HIV low-risk populations. This effect may impact interpretation of phase I trials which typically have small group sizes. The positive association with alcohol use deserves further analysis.
