Though OPV is safe and effective, it can mutate and reacquire neurovirulence in rare circumstances. This can result in vaccine-associated paralytic polio and circulating vaccine-derived polioviruses. Use of tOPV had risk of generating VAPP and seeding new type 2 circulating vaccine-derived polioviruses though wild type 2 virus was eradicated in September 2015. For this reason tOPV vaccine was withdrawn globally in April 2016 and switched to bOPV. cVDPV2 outbreaks have occurred in sixteen countries after cassation of OPV2. Using stockpiled mOPV2 to respond to this situation risks propagating new cVDPVs. IPV induces only limited intestinal mucosal immunity not effective to interrupt fecal-oral route transmission in settings of poor hygiene and sanitation. Therefore, development of novel oral polio vaccine with enhanced genetic stability and lower risk of reversion to neurovirulence compared to current Sabin 2 strains is major priority of global polio eradication Program

Current clinical development plan outlines studies through Phase II development with nOPV2 candidate strains being tested in adult toddler and infant populations who received prior dose of OPV or IPV. No study has been conducted in truly naive newborns with no prior receipt of any polio vaccines

Hypothesis: Vaccinating healthy newborns with novel type 2 polio virus candidate vaccines is safe and can induce putatively protective immune response