The researchers randomized 100 healthy adult volunteers to an experimental Zika vaccine candidate known as Ad26.ZIKV.001 in either one-dose or two-dose regimens of 5×1010 viral particles (low dose) or 1×1011 viral particles (high dose) or placebo. Approximately half (55%) of the participants were women, and 72% were White.
Approximately 80% of patients in both two-dose groups showed antibody responses for a year after vaccination. Geometric mean titers (GMTs) reached a peak of 823.4 in the low-dose/low-dose group and 961.5 in the high-dose/high-dose group. On day 365, the GMTs for these groups were 68.7 and 87.0, respectively.
A single high-dose vaccine achieved a similar level of neutralizing antibody titers, but lower peak neutralizing responses than the two-dose strategies, the researchers noted.
Source: Medscape