Study design and population.
This single-center, double-blind, randomized, placebo-controlled trial of PfSPZ Vaccine was conducted in Baney, Equatorial Guinea, between October 10, 2016 and June 29, 2018 (last study participant visit: January 10, 2018). It had two major components after initial dosing in 18–35-year-old adults: an age de-escalation component to assess safety and immunogenicity in Equatoguinean children and infants and an age escalation component to assess safety and immunogenicity in older adults. In a substudy, a second group of 18–35-year-old adults was immunized with PfSPZ-CVac (non-attenuated PfSPZ attenuated in vivo by coadministration of chloroquine), and the two young adult groups immunized with PfSPZ Vaccine and PfSPZ-CVac underwent CHMI to assess vaccine efficacy (VE).Healthy male and female participants aged 6 months to 65 years were recruited from the Baney District and the city of Malabo on Bioko Island. Participants who met the inclusion and exclusion criteria (