Vaccine-induced T cell responses control Orthoflavivirus challenge infection without neutralizing antibodies in humans.

T cells have been identified as correlates of protection in viral infections. However, the level of vaccine-induced T cells needed and the extent to which they alone can control acute viral infection in humans remain uncertain. Here we conducted a double-blind, randomized controlled trial involving vaccination and challenge in 33 adult human volunteers, using the live-attenuated yellow fever (YF17D) and chimeric Japanese encephalitis-YF17D (JE/YF17D) vaccines.

Live vaccine infection burden elicits adaptive humoral and cellular immunity required to prevent Zika virus infection.

Background: The emergence of Zika virus (ZIKV) as an important cause of congenital and childhood developmental disorders presents another challenge to global health. Efforts to develop a Zika vaccine have begun although vaccine development against flaviviruses, of which ZIKV belongs to, has proven to be time-consuming and challenging. Defining the vaccine attributes that elicit adaptive immune response necessary for preventing ZIKV infection could provide an evidence-based guide to Zika vaccine development.