Damme PV, et al. - Through a double-blind, single-center phase 1 trial of 30 individuals in a purpose-built containment facility at the University of Antwerp Hospital (Antwerp, Belgium), experts assessed the safety and immunogenicity of novel monovalent oral type-2 poliovirus (OPV2) vaccine candidates, the presence, and extent of fecal shedding, and the neurovirulence of shed virus. Both OPV2 vaccines were immunogenic and elevated the median blood titer of serum neutralizing antibodies, and all patients were seroprotected following vaccination. Fair tolerability and no serious adverse events were noted during the study for both vaccines. Severe events were noted in six members who received candidate 1 and nine participants who received candidate 2 and most of these events were elevated blood creatinine phosphokinase, however, they were not followed by clinical signs or symptoms. Vaccine virus was detected in the stools of 15 participants and 13 participants who received vaccine candidate 1 and vaccine candidate 2, respectively. Total shedding was recognized to be larger with candidate 1 vs candidate 2 among all the participants. Reversion to neurovirulence (evaluated as paralysis of transgenic mice) was low in isolates from those who were vaccinated with both candidates. For sustaining global eradication of neurovirulent type-2 polioviruses, the novel OPV2 candidates were concluded as safe and immunogenic in IPV-immunized adults, and the data supported further use of these vaccines.