One drawback of oral polio vaccine (OPV) is the potential reversion to more transmissible, virulent circulating vaccine-derived polioviruses (cVDPVs), which may cause outbreaks of paralytic poliomyelitis. Previous modeling studies of the transmission of cVDPVs assume an unrealistic homogeneous mixing of the population and/or ignore that OPV viruses and cVDPVs compete for susceptibles, which we show is a key to understanding the dynamics of the transmission of cVDPVs. We examined the transmission of OPV viruses and cVDPVs on heterogeneous, dynamic contact networks using differential equation-based and individual-based models. Despite the lower transmissibility, OPV viruses may outcompete more transmissible cVDPVs in the short run by spreading extensively before cVDPVs emerge. If viruses become endemic, however, cVDPVs eventually dominate and force OPV viruses to extinction. This study improves our understanding of the emergence of cVDPVs and helps develop more detailed models to plan a policy to control paralytic polio associated with the continued use of OPV in many countries.
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http://dx.doi.org/10.1016/j.jtbi.2014.09.026 | DOI Listing |
Vaccines (Basel)
January 2025
Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA.
Background/objectives: Conventional live oral poliovirus vaccines (OPVs) effectively prevent poliomyelitis. These vaccines are derived from three attenuated Sabin strains of poliovirus, which can revert within the first week of replication to a neurovirulent phenotype, leading to sporadic cases of vaccine-associated paralytic poliomyelitis (VAPP) among vaccinees and their contacts. A novel OPV2 vaccine (nOPV2) with enhanced genetic stability was developed recently; type 1 and type 3 nOPV strains were engineered using the nOPV2 genome as a backbone by replacing the capsid precursor polyprotein (P1) with that of Sabin strains type 1 and type 3, respectively.
View Article and Find Full Text PDFBMC Infect Dis
January 2025
Bureau de L'Organisation Mondiale de La Santé (OMS), Niamey, Niger.
Background: Recently, a total of 74 circulating vaccine-derived poliovirus (cVDPV) outbreaks were detected in 39 countries, with 672 confirmed Acute Flaccid Paralysis (AFP) cases identified in 27 countries. Despite progress, Niger experienced cVDPV outbreaks in 2018, highlighting the importance of maintaining AFP surveillance as a tool for polio eradication. This analysis aims to comprehensively assess AFP surveillance trends, patterns, and challenges in Niger, offering insights for public health initiatives in conflict-affected contexts.
View Article and Find Full Text PDFVaccines (Basel)
November 2024
Bill & Melinda Gates Foundation, Seattle, WA 98109, USA.
Although wild poliovirus type 2 has been eradicated, the prolonged transmission of the live- attenuated virus contained in the type-2 oral polio vaccine (OPV2) in under-immunized populations has led to the emergence of circulating vaccine-derived poliovirus type 2 (cVDPV2). The novel OPV2 (nOPV2) was designed to be more genetically stable and reduce the chance of cVDPV2 emergence while retaining comparable immunogenicity to the Sabin monovalent OPV2 (mOPV2). This study aimed to estimate the relative reduction in the emergence risk due to the use of nOPV2 instead of mOPV2.
View Article and Find Full Text PDFPathogens
December 2024
World Health Organization Headquarters, Av Appia 10, 1211 Geneva, Switzerland.
Individuals with certain primary immunodeficiency disorders (PID) may be unable to clear poliovirus infection after exposure to oral poliovirus vaccine (OPV). Over time, vaccine-related strains can revert to immunodeficiency-associated vaccine-derived poliovirus (iVDPVs) that can cause paralysis in the patient and potentially spread in communities with low immunity. We reviewed the efforts for detection and management of PID patients with iVDPV infections and the epidemiology through an analysis of 184 cases reported to the World Health Organization (WHO) during 1962-2024 and a review of polio program and literature reports.
View Article and Find Full Text PDFJ Appl Microbiol
January 2025
Department of Genetics, Microbiology and Statistics, School of Biology, Enteric Virus Laboratory, Barcelona 08028, Spain.
Enteroviruses (EVs) are a highly diverse group of viruses multiplying primarily in the gastrointestinal tract and/or the upper respiratory tract, initially distributed in two separate genera: Enterovirus and Rhinovirus, respectively. According to the similarities in genome organization and particle structure, rhinovirus species were later reclassified as also belonging to genus Enterovirus. Human EV infections are usually asymptomatic or causing mild clinical manifestations.
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