Safety and immunogenicity of two novel type 2 oral poliovirus vaccine candidates compared with a monovalent type 2 oral poliovirus vaccine in healthy adults: two clinical trials
A phase 4 historical control study of monovalent OPV2 carried out before global withdrawal of OPV2 (n=100), and a phase 2 study with novel OPV2-c1 and novel OPV2-c2 (n=200) conducted in Belgium found candidates were as safe, well tolerated, and immunogenic as monovalent OPV2.
Source:
The Lancet
SPS commentary:
Also published in The Lancet are the results of two phase 2 clinical trials that assessed the safety and efficacy of the two novel type 2 OPV candidates (OPV2-c1 and OPV2-c2) in infants (aged 18–22 weeks) and young children (aged 1–4 years.
The novel type 2 oral poliovirus vaccines (OPVs) were developed in response to the continued emergence and spread of circulating vaccine-derived type 2 polioviruses and vaccine-associated paralytic poliomyelitis from OPVs). These new vaccines were designed to have similar immunogenicity, improved genetic stability, and less potential to reacquire neurovirulence.
According to an editorial, by early 2020, the point passed at which the best case scenario was possible of stopping all type 2 poliovirus transmission using vaccine supplies produced before OPV2 cessation. It notes this situation puts the world into a new and much more challenging phase that will require careful deliberation of long-term poliovirus vaccine options and management of some insufficient poliovirus vaccine supplies. Furthermore, the disruption in immunisation caused by the COVID-19 pandemic further exacerbates the situation. It suggests these studies represent promising next steps towards the future of global poliovirus control and eradication using better performing OPV strains.