Key result
Japan's 2-dose oral poliovirus vaccine policy yielded >90% seropositivity against virulent type 1 and 2 strains, but only ~60% against type 3 strains, maintaining high herd immunity for 22 years.
Why the study?
Does a 2-dose administration of live oral poliovirus vaccine provide sufficient neutralizing antibody titers against wild and virulent VDPV type 1, 2, 3 strains in residents of Toyama Prefecture, Japan?
Observational
Does a 2-dose administration of live oral poliovirus vaccine provide sufficient neutralizing antibody titers against wild and virulent VDPV type 1, 2, 3 strains in residents of Toyama Prefecture, Japan?
Japan's 2-dose OPV policy maintains high herd immunity against poliovirus types 1, 2, and 3, though a booster for type 3 may be beneficial for adolescents due to lower titers.
Answers are grounded in this paper and cite their sources.
Supports Japan's 2-dose OPV policy for sustained herd immunity; leaves open whether type 3 boosters are warranted in adolescents.
We evaluated the efficacy of Japan's vaccination policy, a 2-dose administration of live oral poliovirus vaccine (OPV) against wild and virulent vaccine-derived poliovirus (VDPV) type 1, 2, 3 strains, by investigating the neutralizing antibody titers of residents in Toyama Prefecture, Japan. Seropositivities against the virulent type 1 and 2 strains were more than 90%, but the values against the virulent type 3 strains were approximately 60%. Also, while geometric mean antibody titers against virulent type 1 and 2 strains were more than 180, those against the virulent type 3 strains were 58-59, and 9-12, in particular, at 10 to 19 y of age. A booster dose of the vaccine for the type 3 virus is recommended for adolescents. However, high herd immunity against type 1, 2 and 3 viruses has been maintained for these 22 y, although the seropositivity against type 3 virus was always lower than other types. Our results suggest that Japan's vaccination policy might be enough to prevent an epidemic of poliomyelitis caused by wild and virulent VDPV type 1, 2, 3 strains, even though the titers against type 3 viruses were the lowest.
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Iwai et al. (2008) conducted an observational in Poliomyelitis. 2-dose administration of live oral poliovirus vaccine (OPV) was evaluated on Seropositivity against virulent type 1, 2, and 3 strains. Japan's 2-dose oral poliovirus vaccine policy yielded >90% seropositivity against virulent type 1 and 2 strains, but only ~60% against type 3 strains, maintaining high herd immunity for 22 years.
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