scholarly journals Evolving epidemiology of poliovirus serotype 2 following withdrawal of the serotype 2 oral poliovirus vaccine

Science ◽  
2020 ◽  
Vol 368 (6489) ◽  
pp. 401-405 ◽  
Author(s):  
G. R. Macklin ◽  
K. M. O’Reilly ◽  
N. C. Grassly ◽  
W. J. Edmunds ◽  
O. Mach ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Statistical Model ◽  
Oral Poliovirus Vaccine ◽  
Outbreak Response ◽  
Wild Poliovirus ◽  
Emergence Date ◽  
Endemic Transmission

Although there have been no cases of serotype 2 wild poliovirus for more than 20 years, transmission of serotype 2 vaccine-derived poliovirus (VDPV2) and associated paralytic cases in several continents represent a threat to eradication. The withdrawal of the serotype 2 component of oral poliovirus vaccine (OPV2) was implemented in April 2016 to stop VDPV2 emergence and secure eradication of all serotype 2 poliovirus. Globally, children born after this date have limited immunity to prevent transmission. Using a statistical model, we estimated the emergence date and source of VDPV2s detected between May 2016 and November 2019. Outbreak response campaigns with monovalent OPV2 are the only available method to induce immunity to prevent transmission. Yet our analysis shows that using monovalent OPV2 is generating more paralytic VDPV2 outbreaks with the potential for establishing endemic transmission. A novel OPV2, for which two candidates are currently in clinical trials, is urgently required, together with a contingency strategy if this vaccine does not materialize or perform as anticipated.

scholarly journals Multiplex PCR-based titration (MPBT) assay for determination of infectious titers of the three Sabin strains of live poliovirus vaccine

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Hasmik Manukyan ◽  
Elvira Rodionova ◽  
Tatiana Zagorodnyaya ◽  
Tsai-Lien Lin ◽  
Konstantin Chumakov ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Clinical Trials ◽  
Cell Cultures ◽  
Multiplex Polymerase Chain Reaction ◽  
Cytopathic Effect ◽  
Oral Poliovirus Vaccine ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Titration Assay ◽  
Serial Dilutions

Abstract Background Conventional assays to titrate polioviruses usually test serial dilutions inoculated into replicate cell cultures to determine a 50% cytopathic endpoint, a process that is both time-consuming and laborious. Such a method is still used to measure potency of live Oral Poliovirus Vaccine during vaccine development and production and in some clinical trials. However, the conventional method is not suited to identify and titrate virus in the large numbers of fecal samples generated during clinical trials. Determining titers of each of the three Sabin strains co-existing in Oral Poliovirus Vaccine presents an additional challenge. Results A new assay using quantitative multiplex polymerase chain reaction as an endpoint instead of cytopathic effect was developed to overcome these limitations. In the multiplex polymerase chain reaction-based titration assay, cell cultures were infected with serial dilutions of test samples, lysed after two-day incubation, and subjected to a quantitative multiplex one-step reverse-transcriptase polymerase chain reaction. All three serotypes of poliovirus were identified in single samples and titers calculated. The multiplex polymerase chain reaction-based titration assay was reproducible, robust and sensitive. Its lower limits of titration for three Sabin strains were 1–5 cell culture 50% infectious doses per ml. We prepared different combinations of three Sabin strains and compared titers obtained with conventional and multiplex polymerase chain reaction-based titration assays. Results of the two assays correlated well and showed similar results and sensitivity. Multiplex polymerase chain reaction-based titration assay was completed in two to 3 days instead of 10 days for the conventional assay. Conclusions The multiplex polymerase chain reaction-based titration (MPBT) is the first quantitative assay that identifies and titrates each of several different infectious viruses simultaneously in a mixture. It is suitable to identify and titrate polioviruses rapidly during the vaccine manufacturing process as a quality control test, in large clinical trials of vaccines, and for environmental surveillance of polioviruses. The MPBT assay can be automated for high-throughput implementation and applied for other viruses including those with no cytopathic effect.

scholarly journals Controlling polio outbreak due to imported wild poliovirus in Indonesia: A success story

2009 ◽  
Vol 49 (4) ◽  
pp. 234 ◽  
Author(s):  
Sumarmo Poorwo Soedarmo ◽  
Sidik Utoro
Keyword(s):  
Acute Flaccid Paralysis ◽  
Polio Eradication ◽  
Outbreak Response ◽  
Success Story ◽  
Wild Poliovirus ◽  
First Case ◽  
Supplementary Immunization Activities ◽  
Stool Samples ◽  
Outbreak Response Immunization

Background As a WHO member state, Indonesia is committed toGlobal Polio Eradication. The last indigenous polio case was found in 1995. However, we faced a big challenge with the occurrence of polio outbreak, beginning with a polio case caused by imported wild poliovirus (WPV) type 1 in Sukabumi in 2005. The virus was originated from Sudan and imported to Indonesia through Saudi Arabia. The outbreak ended with totally 305 cases throughout the country. The last one occurred on 20 February 2006 in Aceh Tenggara District, Nanggroe Aceh Darussalam Province. In addition and separated from the WPV type 1 outbreak, in August 2005, four Acute Flaccid Paralysis (AFP) cases with type 1 Vaccine Derived Poliovirus (VDPV) in stool samples were identified in Madura, East Java Province. The first case was on 9 June 2005 and ended with 45 cases in Madura and another case in Probolinggo District, East Jawa.Objective To report a success of controlling outbreak of importedWPV in Indonesia.Methods Outbreak Response Immunization (ORI) and mopup immunization were conducted immediately. To completelystop the transmission, three rounds of National ImmunizationDays (NIDs) were conducted in 2005 (August, September, andNovember). Some more Supplementary Immunization Activities(SIAs) were conducted in 2006 (mop up in January, NIDs inFebruary and early April, mop ups in June and August 2006).For the VDPV outbreak, ORI of 18,880 children in 83 villagestook place during the first week of August, beside three roundsofNIDs in 2005.Results All activities resulted in satisfactorily coverage, whereeach round always exceeded 95%.Conclusions Those activities were conducted successfully andproven to be effective to stop the outbreak. Then again, Indonesia can be a polio free country in the coming years.

scholarly journals Immunogenicity of Oral Polio Vaccine and Salk Inactive Polio Vaccine Against Xinjiang Imported Type 1 Wild Poliovirus

2019 ◽  
Vol 70 (9) ◽  
pp. 1980-1984 ◽  
Author(s):  
Dongmei Yan ◽  
Dongyan Wang ◽  
Shuangli Zhu ◽  
Yong Zhang ◽  
Xiaolei Li ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Oral Polio Vaccine ◽  
Neutralizing Antibody ◽  
Genomic Sequencing ◽  
Outbreak Response ◽  
Local Immunity ◽  
Wild Poliovirus ◽  
Polio Vaccine ◽  
Antibody Titers

Abstract Background An outbreak of an imported Type 1 wild poliovirus from Pakistan occurred in the Xinjiang Uygur Autonomous Region of China in 2011, although the local immunity status of the oral polio vaccine (OPV) was relatively satisfied. Methods Neutralizing antibody titers against the Xinjiang strain and Sabin 1 strain were measured in 237 sera from 3 groups of fully OPV-vaccinated persons and 1 group of infants fully vaccinated with the inactive polio vaccine (IPV). Additionally, 17 sera collected from 1 Xinjiang poliomyelitis case and his 16 contacts were also tested. Genomic sequencing was conducted the Xinjiang strain. Results The antibody titers against the Xinjiang strain in each of 237 sera were significantly lower than those against the Sabin 1 strain. Notably, 40.0% of children in Group 1 were seronegative against the Xinjiang strain, which indicated that they might play an important role in wild poliovirus transmission, although their antibody titers against the Sabin 1 strain varied between 1:8 and 1:512. Meanwhile, serological results of the Xinjiang poliomyelitis case and his contacts also provided evidence that a proportion of OPV-vaccinated children had indeed been involved in the transmission chain of the Xinjiang outbreak. Genomic sequencing indicated that the Xinjiang strain was greatly distinguishable from the Sabin 1 strain in neutralizing antigenic sites. Conclusion The lack of neutralizing antibodies against the Xinjiang strain in persons vaccinated by OPV may be associated with the transmission of Type 1 wild poliovirus in Xinjiang. Using Salk IPV along with OPV might be considered in a wild poliovirus outbreak response, especially in the countries which continued to have persistent wild poliovirus circulation.

scholarly journals Assessing randomness in case assignment: the case study of the Brazilian Supreme Court

2019 ◽  
Vol 18 (2-3) ◽  
pp. 97-114 ◽  
Author(s):  
Diego Marcondes ◽  
Cláudia Peixoto ◽  
Julio Michael Stern
Keyword(s):  
Clinical Trials ◽  
Statistical Model ◽  
Supreme Court ◽  
Legal System ◽  
Judicial System ◽  
Mathematical Statistics ◽  
Case Assignment ◽  
Legal Case ◽  
Judicial Systems

Abstract Sortition, i.e. random appointment for public duty, has been employed by societies throughout the years as a firewall designated to prevent illegitimate interference between parties in a legal case and agents of the legal system. In judicial systems of modern western countries, random procedures are mainly employed to select the jury, the court and/or the judge in charge of judging a legal case. Therefore, these random procedures play an important role in the course of a case, and should comply with some principles, such as transparency and complete auditability. Nevertheless, these principles are neglected by random procedures in some judicial systems, which are performed in secrecy and are not auditable by the involved parties. The assignment of cases in the Brazilian Supreme Court is an example of such a procedure, for it is performed using procedures unknown to the parties involved in the judicial cases. This article presents a review of how sortition has been historically employed by societies and discusses how Mathematical Statistics may be applied to random procedures of the judicial system, as it has been applied for almost a century on clinical trials, for example. A statistical model for assessing randomness in case assignment is proposed and applied to the Brazilian Supreme Court. As final remarks, guidelines for the development of good randomization procedures are outlined.

scholarly journals Global certification of wild poliovirus eradication: insights from modelling hard-to-reach subpopulations and confidence about the absence of transmission

BMJ Open ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. e023938 ◽  
Author(s):  
Radboud J Duintjer Tebbens ◽  
Dominika A Kalkowska ◽  
Kimberly M Thompson
Keyword(s):  
General Population ◽  
Endemic Equilibrium ◽  
Single Infection ◽  
Susceptible Population ◽  
Wild Poliovirus ◽  
Population Immunity ◽  
Trade Offs ◽  
Time Required ◽  
Endemic Transmission ◽  
Different Characteristics

ObjectiveTo explore the extent to which undervaccinated subpopulations may influence the confidence about no circulation of wild poliovirus (WPV) after the last detected case.Design and participantsWe used a hypothetical model to examine the extent to which the existence of an undervaccinated subpopulation influences the confidence about no WPV circulation after the last detected case as a function of different characteristics of the subpopulation (eg, size, extent of isolation). We also used the hypothetical population model to inform the bounds on the maximum possible time required to reach high confidence about no circulation in a completely isolated and unvaccinated subpopulation starting either at the endemic equilibrium or with a single infection in an entirely susceptible population.ResultsIt may take over 3 years to reach 95% confidence about no circulation for this hypothetical population despite high surveillance sensitivity and high vaccination coverage in the surrounding general population if: (1) ability to detect cases in the undervaccinated subpopulation remains exceedingly small, (2) the undervaccinated subpopulation remains small and highly isolated from the general population and (3) the coverage in the undervaccinated subpopulation remains very close to the minimum needed to eradicate. Fully-isolated hypothetical populations of 4000 people or less cannot sustain endemic transmission for more than 5 years, with at least 20 000 people required for a 50% chance of at least 5 years of sustained transmission in a population without seasonality that starts at the endemic equilibrium. Notably, however, the population size required for persistent transmission increases significantly for realistic populations that include some vaccination and seasonality and/or that do not begin at the endemic equilibrium.ConclusionsSignificant trade-offs remain inherent in global polio certification decisions, which underscore the need for making and valuing investments to maximise population immunity and surveillance quality in all remaining possible WPV reservoirs.

scholarly journals Serotype 2 oral poliovirus vaccine (OPV2) choices and the consequences of delaying outbreak response

Vaccine ◽  
2021 ◽  
Author(s):  
Dominika A. Kalkowska ◽  
Mark A. Pallansch ◽  
Steven G.F. Wassilak ◽  
Stephen L. Cochi ◽  
Kimberly M. Thompson
Keyword(s):  
Oral Poliovirus Vaccine ◽  
Outbreak Response

Monovalent type 1 oral poliovirus vaccine among infants in India: Report of two randomized double-blind controlled clinical trials

Vaccine ◽  
2011 ◽  
Vol 29 (34) ◽  
pp. 5793-5801 ◽  
Author(s):  
T. Jacob John ◽  
Hemant Jain ◽  
Kanithi Ravishankar ◽  
A. Amaresh ◽  
Harish Verma ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Oral Poliovirus Vaccine ◽  
Controlled Clinical Trials ◽  
Double Blind
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