Hiromasa Okayasu

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OBJECTIVES To evaluate oral poliovirus vaccine (OPV) coverage of the November 2009 round in five Northern Nigeria states with ongoing wild poliovirus transmission using clustered lot quality assurance sampling (CLQAS). METHODS We selected four local government areas in each pre-selected state and sampled six clusters of 10 children in each Local(More)
After polio eradication is achieved, the use of live-attenuated oral poliovirus vaccine (OPV) must be discontinued because of the inherent risk of the Sabin strains to revert to neurovirulence and reacquire greater transmissibility that could potentially result in the reestablishment of polio transmission. In 2008, the World Health Assembly mandated that(More)
Since the resolution of the World Assembly in 1988 to eradicate polio globally, substantial progress toward this target has been achieved, but the final goal remains elusive. India and other tropical developing countries present a unique challenge because of the much lower oral poliovirus vaccine (OPV) immunogenicity compared to industrialized countries,(More)
Monitoring the quality of supplementary immunization activities (SIAs) is a key tool for polio eradication. Regular monitoring data, however, are often unreliable, showing high coverage levels in virtually all areas, including those with ongoing virus circulation. To address this challenge, lot quality assurance sampling (LQAS) was introduced in 2009 as an(More)
Chronic prolonged excretion of vaccine-derived polioviruses by immunodeficient persons (iVDPV) presents a personal risk of poliomyelitis to the patient as well as a programmatic risk of delayed global eradication. Poliovirus antiviral drugs offer the only mitigation of these risks. Antiviral agents may also have a potential role in the management of(More)
BACKGROUND Seroprevalence studies provide important data on performance of immunization programs, susceptible groups and populations at-risk of future outbreaks. Identifying risk factors that affect seroconversion of the oral polio vaccine (OPV) will enable the polio eradication initiatives to increase seroprevalence. This paper describes the first(More)
BACKGROUND An inactivated poliovirus vaccine (IPV) based on attenuated poliovirus strains (Sabin-1, -2 and -3) was developed for technology transfer to manufacturers in low- and middle-income countries in the context of the global polio eradication initiative. METHOD Safety and immunogenicity of Sabin-IPV (sIPV) was evaluated in a double-blind,(More)
The Global Polio Eradication Initiative (GPEI) currently based on use of oral poliovirus vaccine (OPV) has identified suboptimal immunogenicity of this vaccine as a major impediment to eradication, with a failure to induce protection against paralytic poliomyelitis in certain population segments in some parts of the world. The Mucosal Immunity and(More)
INTRODUCTION We conducted a follow-on study to a phase I randomized, controlled trial conducted in Cuba, 2012, to assess the persistence of poliovirus antibodies at 21-22 months following booster dose of Sabin-IPV compared to Salk-IPV in adults who had received multiple doses of oral poliovirus vaccine (OPV) during childhood. METHODS In 2012, 60 healthy(More)
BACKGROUND An inactivated poliovirus vaccine (IPV) based on attenuated poliovirus strains (Sabin-1, -2 and -3) was developed for technology transfer to manufacturers in low- and middle income countries in the context of the Global Polio Eradication Initiative. METHOD Safety and immunogenicity of the Sabin-IPV was evaluated in a double-blind, randomized,(More)