Novel live type 1, 3 oral polio vaccines show promise in phase 1 trial

New Delhi, Aug 16 The novel live attenuated type 1 and 3 oral polio vaccines (nOPV1 and nOPV3) are safe and elicit good immune response, results of a phase 1 randomized controlled trial have shown.

The study, published in The Lancet Infectious Diseases, showed that nOPV1 and nOPV3 have a favourable safety profile. It also produced a comparable immune response and viral-shedding profile as the homotypic monovalent (single-strain) Sabin-strain oral vaccines (mOPVs).

“This first-in-human trial of nOPV1 and nOPV3 showed that both vaccine candidates are safe and well tolerated in healthy adults and can elicit neutralising antibody responses similar to those elicited by mOPV1 and mOPV3, respectively,” said researchers, including those from the University of North Carolina.

The findings are based on a randomised trial of 205 adults at four centres in the US. The participants were randomly assigned to receive at least one dose of nOPV or mOPV.

Inactivated poliovirus vaccine participants received one dose of nOPV1 or mOPV1 (cohort 1) or nOPV3 or mOPV3 (cohort 3), and OPV participants received two doses of nOPV1 or mOPV1 (cohort 2) or nOPV3 or mOPV3 (cohort 4) 28 days apart.

The magnitude and duration of nOPV shedding were not higher than with Sabin controls, revealed the researchers in the paper.

“We also observed a reduction of shedding following the second dose, which is consistent with enhancement of intestinal immunity,” they added.

The successful deployment of nOPV2 to combat type 2 circulating vaccine-derived polioviruses (VDPVs) suggested that use of such novel vaccines could be effective in the control of circulating VDPV outbreaks after the cessation of vaccines containing Sabin-strain types 1 and 3 polioviruses.

nOPVs can support the Global Polio Eradication Initiative's Polio Endgame Strategy by providing vaccines less likely to be tied to vaccine-associated paralytic polio and seeding of new circulating vaccine-derived polioviruses (VDPVs), the researchers said.

"The safety and immunogenicity evidence generated for nOPV1 and nOPV3 in this phase 1 clinical study were sufficient to justify the now ongoing phase 2 studies in geographically relevant target populations of previously vaccinated children and infants, as well as vaccine-naive neonates," the researchers said.

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