SciCombinator

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Concept: OPV AIDS hypothesis

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We examined the introduction of diphtheria-tetanus-pertussis (DTP) and oral polio vaccine (OPV) in an urban community in Guinea-Bissau in the early 1980s.

Concepts: Vaccine, Poliomyelitis, Polio vaccine, Experiment, Introduction, Poliomyelitis eradication, OPV AIDS hypothesis

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The WHO recommends complete withdrawal of Oral Polio Vaccine (OPV) Type 2 by April 2016 globally and replacing with at least one dose of Inactivated Poliovirus Vaccine (IPV). However, high-cost, limited supply of IPV, persistent circulating vaccine-derived polioviruses transmission and need for subsequent boosters remain unresolved. To meet this critical need, a novel strategy of a low cost cold-chain free plant-made viral protein 1 (VP1) subunit oral booster vaccine after single IPV dose is reported. Codon optimization of the VP1 gene enhanced expression by 50-fold in chloroplasts. Oral boosting of VP1 expressed in plant cells with plant-derived adjuvants after single priming with IPV significantly increased VP1-IgG1 and VP1-IgA titers when compared to lower IgG1 or negligible IgA titers with IPV injections. IgA plays a pivotal role in polio eradication because of its transmission through contaminated water or sewer systems. Neutralizing antibody titers (~3.17-10.17 log2 titer) and serpositivity (70-90%) against all three poliovirus Sabin serotypes were observed with two doses of IPV and plant-cell oral boosters but single dose of IPV resulted in poor neutralization. Lyophilized plant cells expressing VP1 stored at ambient temperature maintained efficacy and preserved antigen folding/assembly indefinitely, thereby eliminating cold-chain currently required for all vaccines. Replacement of OPV with this booster vaccine and the next steps in clinical translation of FDA approved antigens and adjuvants are discussed. This article is protected by copyright. All rights reserved.

Concepts: Immune system, Vaccine, Vaccination, Poliomyelitis, Polio vaccine, Poliomyelitis eradication, OPV AIDS hypothesis, Poliovirus

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Because oral polio vaccine has been associated with cases of paralysis, it is essential to discontinue its use after polio eradication has been certified. The first step is a shift from a trivalent OPV to a bivalent one, which requires a multipronged global strategy.

Concepts: Vaccine, Vaccination, Poliomyelitis, Polio vaccine, The Final, World, Poliomyelitis eradication, OPV AIDS hypothesis

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To secure a polio-free world, the live attenuated oral poliovirus vaccine (OPV) will eventually need to be replaced with inactivated poliovirus vaccines (IPV). However, current IPV delivery is less suitable for campaign use than OPV, and more expensive. We are progressing a microarray patch delivery platform, the Nanopatch, as an easy-to-use device to administer vaccines, including IPV. The Nanopatch contains an ultra-high density array (10,000/cm(2)) of short (~230 μm) microprojections that delivers dry coated vaccine into the skin. Here, we compare the relative immunogenicity of Nanopatch immunisation versus intramuscular injection in rats, using monovalent and trivalent formulations of IPV. Nanopatch delivery elicits faster antibody response kinetics, with high titres of neutralising antibody after just one (IPV2) or two (IPV1 and IPV3) immunisations, while IM injection requires two (IPV2) or three (IPV1 and IPV3) immunisations to induce similar responses. Seroconversion to each poliovirus type was seen in 100% of rats that received ~1/40th of a human dose of IPV delivered by Nanopatch, but not in rats given ~1/8th or ~1/40th dose by IM injection. Ease of administration coupled with dose reduction observed in this study suggests the Nanopatch could facilitate inexpensive IPV vaccination in campaign settings.

Concepts: Immune system, Antibody, Vaccine, Vaccination, Polio vaccine, Immunology, Route of administration, OPV AIDS hypothesis

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Six different adjuvants, each in combination with inactivated polio vaccine (IPV) produced with attenuated Sabin strains (sIPV), were evaluated for their ability to enhance virus neutralizing antibody titres (VNTs) in the rat potency model. The increase of VNTs was on average 3-, 15-, 24-fold with adjuvants after one immunization (serotypes 1, 2, and 3, respectively). Also after a boost immunization the VNTs of adjuvanted sIPV were on average another 7-20-27 times higher than after two inoculations of sIPV without adjuvant. The results indicate that it is feasible to increase the potency of inactivated polio vaccines by using adjuvants.

Concepts: Immune system, Vaccine, Poliomyelitis, Polio vaccine, Immunologic adjuvant, Poliomyelitis eradication, OPV AIDS hypothesis, Albert Sabin

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With the circulation of wild poliovirus (WPV) types 1 and 3 continuing more than a decade after the original goal of eradicating all three types of WPVs by 2000, policymakers consider many immunization options as they strive to stop transmission in the remaining endemic and outbreak areas and prevent reintroductions of live polioviruses into nonendemic areas. While polio vaccination choices may appear simple, our analysis of current options shows remarkable complexity. We offer important context for current and future polio vaccine decisions and policy analyses by developing decision trees that clearly identify potential options currently used by countries as they evaluate national polio vaccine choices. Based on a comprehensive review of the literature we (1) identify the current vaccination options that national health leaders consider for polio vaccination, (2) characterize current practices and factors that appear to influence national and international choices, and (3) assess the evidence of vaccine effectiveness considering sources of variability between countries and uncertainties associated with limitations of the data. With low numbers of cases occurring globally, the management of polio risks might seem like a relatively low priority, but stopping live poliovirus circulation requires making proactive and intentional choices to manage population immunity in the remaining endemic areas and to prevent reestablishment in nonendemic areas. Our analysis shows remarkable variability in the current national polio vaccine product choices and schedules, with combination vaccine options containing inactivated poliovirus vaccine and different formulations of oral poliovirus vaccine making choices increasingly difficult for national health leaders.

Concepts: Immune system, Vaccine, Vaccination, Poliomyelitis, Polio vaccine, Poliomyelitis eradication, OPV AIDS hypothesis, Poliovirus

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ABSTRACT  Live attenuated oral polio vaccine (OPV) and inactivated polio vaccine (IPV) are the tools being used to achieve eradication of wild polio virus. Because OPV can rarely cause paralysis and generate revertant polio strains, IPV will have to replace OPV after eradication of wild polio virus is certified to sustain eradication of all polioviruses. However, uncertainties remain related to IPV’s ability to induce intestinal immunity in populations where fecal-oral transmission is predominant. Although substantial effectiveness and safety data exist on the use and delivery of OPV and IPV, several new research initiatives are currently underway to fill specific knowledge gaps to inform future vaccination policies that would assure polio is eradicated and eradication is maintained.

Concepts: Enterovirus, Vaccine, Vaccination, Poliomyelitis, Polio vaccine, Smallpox, OPV AIDS hypothesis, Poliovirus

18

When included in a sequential polio vaccination schedule, inactivated polio vaccine (IPV) reduces the risk for vaccine-associated paralytic poliomyelitis (VAPP), a rare adverse event associated with receipt of oral poliovirus vaccine (OPV). During January 2014, the World Health Organization (WHO) recommended introduction of at least 1 IPV dose into routine immunization schedules in OPV-using countries (1). The Polio Eradication and Endgame Strategic Plan 2013-2018 recommended completion of IPV introduction in 2015 and globally synchronized withdrawal of OPV type 2 in 2016 (2). Introduction of 1 dose of IPV into Beijing’s Expanded Program on Immunization (EPI) on December 5, 2014 represented China’s first province-wide IPV introduction. Coverage with the first dose of polio vaccine was maintained from 96.2% to 96.9%, similar to coverage with the first dose of diphtheria and tetanus toxoids and pertussis vaccine (DTP) (96.5%-97.2%); the polio vaccine dropout rate (the percentage of children who received the first dose of polio vaccine but failed to complete the series) was 1.0% in 2015 and 0.4% in 2016. The use of 3 doses of private-sector IPV per child decreased from 18.1% in 2014, to 17.4% in 2015, and to 14.8% in 2016. No cases of VAPP were identified during 2014-2016. Successful introduction of IPV into the public sector EPI program was attributed to comprehensive planning, preparation, implementation, robust surveillance for adverse events after immunization (AEFI), and monitoring of vaccination coverage. This evaluation provided information that helped contribute to the expansion of IPV use in China and in other OPV-using countries.

Concepts: Vaccine, Vaccination, Poliomyelitis, Polio vaccine, Tetanus, Poliomyelitis eradication, OPV AIDS hypothesis, Poliovirus

13

In a Perspective linked to the research article by Isobel Blake and colleagues, Elizabeth Miller and T. Jacob John discuss the path towards global polio eradication and the challenges, strategies, and necessary precautions around oral polio vaccine cessation.

Concepts: Public health, Vaccine, Poliomyelitis, Polio vaccine, Research, Smallpox, Poliomyelitis eradication, OPV AIDS hypothesis

13

Polio eradication is progressing rapidly, and the live attenuated Sabin strains in the oral poliovirus vaccine (OPV) are being removed sequentially, starting with type 2 in April 2016. For risk mitigation, countries are introducing inactivated poliovirus vaccine (IPV) into routine vaccination programs. After April 2016, monovalent type 2 OPV will be available for type 2 outbreak control. Because the current IPV is not suitable for house-to-house vaccination campaigns (the intramuscular injections require health professionals), we developed a high-density microprojection array, the Nanopatch, delivered monovalent type 2 IPV (IPV2) vaccine to the skin. To assess the immunogenicity of the Nanopatch, we performed a dose-matched study in rats, comparing the immunogenicity of IPV2 delivered by intramuscular injection or Nanopatch immunisation. A single dose of 0.2 D-antigen units of IPV2 elicited protective levels of poliovirus antibodies in 100% of animals. However, animals receiving IPV2 by IM required at least 3 immunisations to reach the same neutralising antibody titres. This level of dose reduction (1/40th of a full dose) is unprecedented for poliovirus vaccine delivery. The ease of administration coupled with the dose reduction observed in this study points to the Nanopatch as a potential tool for facilitating inexpensive IPV for mass vaccination campaigns.

Concepts: Immune system, Antibody, Vaccine, Vaccination, Poliomyelitis, Polio vaccine, Immunology, OPV AIDS hypothesis