Fecal samples were weekly obtained from children under 3 years of age to isolate non-polio poliovirus and enterovirus and to expand the knowledge on circulation of vaccine-derived viruses during mass campaigns. The steady vaccination schedules allow the circulation of these viruses for long periods of time. The interference of non-polio enterovirus by vaccine poliovirus was demonstrated in children. However, the low percentages of non-polio enterovirus did not show significant differences whereas these differences were significant in high percentages of vaccine poliovirus isolated in children under one year-old in comparison with those of 1 and 2 years of age. Based on this contradiction, mathematical calculations estimated the silent circulation of poliovirus that in turn made it possible to draw simulated curves. The results were later confirmed in another research work by using immunological methods.
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BMC 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 PDFEuro Surveill
January 2025
Department for Communicable Disease Prevention and Control, Chief Sanitary Inspectorate, Warsaw, Poland.
In October and December 2024, circulating vaccine-derived poliovirus type 2 (cVDPV2) was detected from two wastewater samples in Poland during routine environmental surveillance. The first isolate was characterised and matched previous cVDPV2 isolates detected in Spain in September, as well as in Germany, Finland, and the United Kingdom in November and December 2024. In response to the event, active surveillance for acute flaccid paralysis (AFP) has been strengthened, and the frequency of environmental sample collection has been increased.
View Article and Find Full Text PDFVaccines (Basel)
November 2024
Sanofi Vaccines Medical, 14 Espace Henri Vallee, 69007 Lyon, France.
The Global Polio Eradication Initiative (GPEI), launched in 1988, has successfully reduced wild poliovirus (WPV) cases by over 99.9%, with WPV type 2 and WPV3 declared eradicated in 2015 and 2019, respectively. However, as of 2024, WPV1 remains endemic in Afghanistan and Pakistan.
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 PDFPan Afr Med J
December 2024
World Health Organization, Expanded Programme on Immunization, Maternal Child Health and Nutrition, Addis Ababa, Ethiopia.
Introduction: following the detection of vaccine-derived poliovirus in 2019 in Ethiopia, response activities have been conducted including strengthening disease surveillance activities.
Methods: trend analysis study design of acute flaccid paralysis and measles surveillance data for the years 2021 and 2022 for Southwest Ethiopia Region was used. The non-polio acute flaccid paralysis (AFP) rate and stool adequacy rates were used to assess the AFP surveillance.
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