Participants at HJF Medical Research International in Abuja, Nigeria, have been vaccinated in the first Phase 2 clinical trial of a Lassa fever virus (LASV) vaccine candidate to date, according to IAVI, a nonprofit scientific research organization and the trial sponsor. The study (IAVI C105/PREVAIL15) is funded by CEPI, an innovative global partnership working to accelerate the development of vaccines against epidemic and pandemic threats.