Status: Funded - Open
Ngu Abanda, PhD
BACKGROUND: The long-term outcome of a single dose of the yellow fever vaccine administered to infants aged 9-12 months is unknown. A recent study suggests that about ~50% of infants vaccinated at 9-12months of age will lack neutralizing antibodies to yellow fever virus 6 years post vaccination. GAP: The absence of neutralizing antibodies (absence of protection) may suggest increase susceptibility to yellow fever infection and an increase in the number of cases but that is not the case. This observation raises the question: does the yellow fever vaccine induce a long-lasting immune response and are neutralizing antibodies the best correlate of this long-lasting protective immunity. We propose to characterize the yellow fever vaccine induced humoral (B cells) and cellular (T cell) immune response over time in infants. HYPOTHESIS: We hypothesize that the yellow fever vaccine administered at 9-12months elicits a polyfunctional initial and long-lasting antibody and T cell response and that measuring neutralizing antibodies only cannot define this immune response METHODS: To investigate our hypothesis, we would use biological samples (plasma, PBMCs) obtained from HIV+ and HIV- infants enrolled within the PEDIACAM study. The PEDIACAM study is a prospective cohort of infants born live to HIV+ and HIV- mothers enrolled between 2007-2011 mostly during the first week of life and followed to date. RESULTS: Pending. IMPACT: This study will provide supporting evidence on the long-term outcome of the one dose yellow fever vaccine policy in infants. Secondly, the study will define correlates of immune protection that will be helpful in evaluating and improving current and new yellow fever vaccines This will be a collaborative study between the University of Hawaii, at Manoa, USA and Centre Pasteur of Cameroon.