Environmental Surveillance for Risk Assessment in the Context of a Phase 2 Clinical Trial of Type 2 Novel Oral Polio Vaccine in Panama.

Environmental surveillance was recommended for risk mitigation in a novel oral polio vaccine-2 (nOPV2) clinical trial (M5-ABMG) to monitor excretion, potential circulation, and loss of attenuation of the two nOPV2 candidates. The nOPV2 candidates were developed to address the risk of poliovirus (PV) type 2 circulating vaccine-derived poliovirus (cVDPV) as part of the global eradication strategy. Between November 2018 and January 2020, an environmental surveillance study for the clinical trial was conducted in parallel to the M5-ABMG clinical trial at five locations in Panama. The collection sites were located upstream from local treatment plant inlets, to capture the excreta from trial participants and their community. Laboratory analyses of 49 environmental samples were conducted using the two-phase separation method. Novel OPV2 strains were not detected in sewage samples collected during the study period. However, six samples were positive for Sabin-like type 3 PV, two samples were positive for Sabin-like type 1 PV, and non-polio enteroviruses NPEVs were detected in 27 samples. One of the nOPV2 candidates has been granted Emergency Use Listing by the World Health Organization and initial use started in March 2021. This environmental surveillance study provided valuable risk mitigation information to support the Emergency Use Listing application.

Updated Characterization of Outbreak Response Strategies for 2019-2029: Impacts of Using a Novel Type 2 Oral Poliovirus Vaccine Strain.

Delays in achieving the global eradication of wild poliovirus transmission continue to postpone subsequent cessation of all oral poliovirus vaccine (OPV) use. Countries must stop OPV use to end all cases of poliomyelitis, including vaccine-associated paralytic polio (VAPP) and cases caused by vaccine-derived polioviruses (VDPVs). The Global Polio Eradication Initiative (GPEI) coordinated global cessation of all type 2 OPV (OPV2) use in routine immunization in 2016 but did not successfully end the transmission of type 2 VDPVs (VDPV2s), and consequently continues to use type 2 OPV (OPV2) for outbreak response activities. Using an updated global poliovirus transmission and OPV evolution model, we characterize outbreak response options for 2019-2029 related to responding to VDPV2 outbreaks with a genetically stabilized novel OPV (nOPV2) strain or with the currently licensed monovalent OPV2 (mOPV2). Given uncertainties about the properties of nOPV2, we model different assumptions that appear consistent with the evidence on nOPV2 to date. Using nOPV2 to respond to detected cases may reduce the expected VDPV and VAPP cases and the risk of needing to restart OPV2 use in routine immunization compared to mOPV2 use for outbreak response. The actual properties, availability, and use of nOPV2 will determine its effects on type 2 poliovirus transmission in populations. Even with optimal nOPV2 performance, countries and the GPEI would still likely need to restart OPV2 use in routine immunization in OPV-using countries if operational improvements in outbreak response to stop the transmission of cVDPV2s are not implemented effectively.

Comparison of Illumina MiSeq and the Ion Torrent PGM and S5 platforms for whole-genome sequencing of picornaviruses and caliciviruses.

Next-generation sequencing is a powerful tool for virological surveillance. While Illumina® and Ion Torrent® sequencing platforms are used extensively for generating viral RNA genome sequences, there is limited data comparing different platforms. The Illumina MiSeq, Ion Torrent PGM and Ion Torrent S5 platforms were evaluated using a panel of sixteen specimens containing picornaviruses and human caliciviruses (noroviruses and sapoviruses). The specimens were processed, using combinations of three library preparation and five sequencing kits, to assess the quality and completeness of assembled viral genomes, and an estimation of cost per sample to generate the data was calculated. The choice of library preparation kit and sequencing platform was found to impact the breadth of genome coverage and accuracy of consensus viral genomes. The Ion Torrent S5 510 chip runs produced more reads at a lower cost per sample than the highest output Ion Torrent PGM 318 chip run, and generated the highest proportion of reads for enterovirus D68 samples. However, indels at homopolymer regions impacted the accuracy of consensus genome sequences. For lower throughput sequencing runs (i.e., Ion Torrent 510 and Illumina MiSeq Nano V2), the cost per sample was lower on the MiSeq platform, whereas with higher throughput runs (Ion Torrent 530 and Illumina MiSeq V2) there is less of a difference in the cost per sample between the two sequencing platforms ($5.47-$10.25 more per sample for an Ion Torrent 530 chip run when multiplexing 24 samples). These findings suggest that the Ion Torrent S5 and Illumina MiSeq platforms are both viable options for genomic sequencing of RNA viruses, each with specific advantages and tradeoffs.

Assessment of immunity to polio among Rohingya children in Cox's Bazar, Bangladesh, 2018: A cross-sectional survey.

BACKGROUND: We performed a cross-sectional survey in April-May 2018 among Rohingya in Cox's Bazar, Bangladesh, to assess polio immunity and inform vaccination strategies. METHODS AND FINDINGS: Rohingya children aged 1-6 years (younger group) and 7-14 years (older group) were selected using multi-stage cluster sampling in makeshift settlements and simple random sampling in Nayapara registered camp. Surveyors asked parents/caregivers if the child received any oral poliovirus vaccine (OPV) in Myanmar and, for younger children, if the child received vaccine in any of the 5 campaigns delivering bivalent OPV (serotypes 1 and 3) conducted during September 2017-April 2018 in Cox's Bazar. Dried blood spot (DBS) specimens were tested for neutralizing antibodies to poliovirus types 1, 2, and 3 in 580 younger and 297 older children. Titers ≥ 1:8 were considered protective. Among 632 children (335 aged 1-6 years, 297 aged 7-14 years) enrolled in the study in makeshift settlements, 51% were male and 89% had arrived after August 9, 2017. Among 245 children (all aged 1-6 years) enrolled in the study in Nayapara, 54% were male and 10% had arrived after August 9, 2017. Among younger children, 74% in makeshift settlements and 92% in Nayapara received >3 bivalent OPV doses in campaigns. Type 1 seroprevalence was 85% (95% CI 80%-89%) among younger children and 91% (95% CI 86%-95%) among older children in makeshift settlements, and 92% (88%-95%) among younger children in Nayapara. Type 2 seroprevalence was lower among younger children than older children in makeshift settlements (74% [95% CI 68%-79%] versus 97% [95% CI 94%-99%], p < 0.001), and was 69% (95% CI 63%-74%) among younger children in Nayapara. Type 3 seroprevalence was below 75% for both age groups and areas. The limitations of this study are unknown routine immunization history and poor retention of vaccination cards. CONCLUSIONS: Younger Rohingya children had immunity gaps to all 3 polio serotypes and should be targeted by future campaigns and catch-up routine immunization. DBS collection can enhance the reliability of assessments of outbreak risk and vaccination strategy impact in emergency settings.

Characterising the costs of the Global Polio Laboratory Network: a survey-based analysis.

OBJECTIVE: To characterise the costs, including for environmental surveillance (ES), of the Global Polio Laboratory Network (GPLN) that provides laboratory support to the Global Polio Eradication Initiative (GPEI). DESIGN AND PARTICIPANTS: We conducted a survey of the network across 92 countries of the 146 GPLN laboratories plus three non-GPLN laboratories that concentrate environmental samples to collect information about their activities, characteristics and costs during 2016. We estimate the total costs using regression of reported responses and complementing the findings with GPEI data. RESULTS: We received responses from 132 (89%) of the 149 laboratories, with variable response rates for individual questions. We estimate that processing samples of patients with acute flaccid paralysis leads to total costs of approximately $28 million per year (2016 US$) based on extrapolation from reported costs of $16 million, of which 61% were supported by internal (national) funds. Fifty-nine (45%) of the 132 responding laboratories reported supporting ES and we estimate an additional $5.3 million of recurring costs for ES activities performed by the laboratories. The reported costs do not include an estimated additional $10 million of annual global and regional costs to coordinate and support the GPLN. On average, the staff supported by funding for polio in the responding laboratories spent 30% of their time on non-polio activities. We estimate total costs for laboratory support of approximately $43 million (note that this estimate does not include any field or other non-laboratory costs of polio surveillance). CONCLUSIONS: Although countries contribute significantly to the GPLN financing, many laboratories currently depend on GPEI funds, and these laboratories also support the laboratory component of surveillance activities for other diseases. Sustaining critical global surveillance for polioviruses and transitioning support for other disease programmes will require continued significant funding after polio certification.

Progress of polio eradication and containment requirements after eradication.

Wild poliovirus (WPV) is nearing eradication, and only three countries have never interrupted WPV transmission (Pakistan, Afghanistan, and Nigeria). WPV2 was last detected in 1999, and it was declared eradicated in 2015. WPV3 has not been detected since 2012. Since 2016, WPV1 has been detected in only two countries (Afghanistan and Pakistan), with only 22 cases reported in 2017 and 12 cases reported in 2018 (as of July 10). Because of WPV2 eradication and the risk of emergence of type 2 vaccine-derived polioviruses from continued use of trivalent oral polio vaccine (OPV), trivalent OPV was replaced by bivalent OPV (types 1 and 3) in a globally coordinated effort in 2016. WPV2 eradication and trivalent OPV cessation also mean that breach of containment in a facility working with type 2 poliovirus is now a major risk to reseed type 2 circulation in the community. As a result, the World Health Organization has developed a "Global Action Plan to minimize poliovirus facility-associated risk after type-specific eradication of wild polioviruses and sequential cessation of oral polio vaccine use." Because poliovirus has long been used as a standard for qualification of intravenous immunoglobulin, disinfectant products, and sanitation methods, poliovirus containment has implications far beyond poliovirus laboratories.

Assessment of poliovirus antibody seroprevalence in high risk areas for vaccine derived poliovirus transmission in Madagascar.

BACKGROUND: Vaccine-derived polioviruses (VDPV) outbreaks typically occur in areas of low poliovirus immunity. Madagascar successfully eradicated wild poliovirus in 1997; however, multiple VDPV outbreaks have occurred since then, and numerous vaccination campaigns have been carried out to control the VDPV outbreaks. We conducted a survey of poliovirus neutralizing antibodies among Malagasy children to assess performance of vaccination campaigns and estimate the risk of future VDPV outbreaks. METHODS: This was a random community survey in children aged 6-11 months, 36-59 months and 5-14 years of age in high risk areas of Madagascar (Mahajanga, Toliara, Antsalova, and Midongy-atsimo); and in a reference area (Antananarivo). After obtaining informed consent, basic demographic and vaccination history, 2 mL of peripheral blood were collected. Neutralizing antibodies against all three poliovirus serotypes were detected by using a standard microneutralization assay. RESULTS: There were 1500 children enrolled and 1496 (>99%) provided sufficient quantity of blood for analysis. Seroprevalence for poliovirus type 1 (PV1) was >90% in all age groups and study areas. PV2 seroprevalence ranged between 75-100%; it was lowest in the youngest age group in Midongy and Toliara. PV3 seroprevalence ranged between 79-100%. Seroprevalence in the reference area was not significantly different from polio high risk sites. DISCUSSION: Madagascar achieved high population immunity. In order to preserve these gains, routine immunization needs to be strengthened. Currently, the risk of new VDPV emergences in Madagascar appears low.

Assessment of poliovirus antibody seroprevalence in polio high risk areas of West Africa.

We conducted a serological survey of anti-polio antibodies in polio high-risk areas of Mali, Guinea and Cote d'Ivoire to assess risk of future poliovirus outbreaks. Random community sampling of children 6-11 and 36-48 months-old was conducted; neutralizing antibodies against poliovirus were detected using microneutralization assay. We analysed 1059/1064 (99.5%) of enrolled children. Seroprevalence to poliovirus type 1 (PV1) across all age groups and locations ranged between 92 and 100%, for PV2 it was 77-100%, and 89-95% for PV3. PV2 seroprevalence in the younger age group in Guinea and Cote d'Ivoire was <80%. History of <4 polio vaccine doses and acute malnutrition were associated with seronegativity (OR = 2.1 CI95% = 1.5-3.1, OR = 1.8 CI95% = 1.1-3.3 respectively). The risk of poliovirus outbreak following importation is low because of high population immunity to PV1, however, due to large cohort of PV2 seronegative children any future detection of vaccine-derived poliovirus type 2 requires urgent response to arrest rapid spread.

Enterovirus D68 in Critically Ill Children: A Comparison With Pandemic H1N1 Influenza.

OBJECTIVE: In 2014, the Unites States experienced an outbreak of enterovirus D68 associated with severe respiratory illness. The clinical characteristics associated with severe illness from enterovirus D68 during this outbreak compared with those associated with the 2009 H1N1 influenza virus outbreak are unknown. DESIGN AND SETTING: In this retrospective cohort study, we characterized the clinical features of children with enterovirus D68 admitted to the PICU between August 1, 2014, and November 1, 2014, and compared them with critically ill children infected with H1N1 influenza during the pandemic admitted between May 1, 2009, and January 31, 2010. PATIENTS: PICU patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Ninety-seven severely ill children with enterovirus D68 infections were compared with 68 children infected with H1N1 influenza during the 2009 pandemic. Children with enterovirus D68 were more likely to have asthma (62% vs 23%; p < 0.001) and present with reactive airway disease exacerbations, with greater receipt of albuterol (94% vs 49%) and steroids (89% vs 40%; p < 0.0001 for both). Although more children with enterovirus D68 were admitted to the ICU compared with those with H1N1 influenza, they had a shorter hospital length of stay (4 vs 7 d; p < 0.0001), with lower intubation rates (7% vs 44%), vasopressor use (3% vs 32%), acute respiratory distress syndrome (3% vs 24%), shock (0% vs 16%), and death (0% vs 12%; p < 0.05 for all). Compared with children with other enteroviruses and rhinoviruses, children with enterovirus D68 were more likely to have a history of asthma (64% vs 45%) or multiple prior wheezing episodes (54% vs 34%; p < 0.01 for both). CONCLUSIONS: Critically ill children with enterovirus D68 were more likely to present with reactive airway disease exacerbations, whereas children with H1N1 influenza were more likely to present with pneumonia. Compared with the pandemic H1N1 influenza outbreak, the enterovirus D68 outbreak resulted in more children requiring admission to the ICU, but was associated with less severe outcomes.

Progress in the development of poliovirus antiviral agents and their essential role in reducing risks that threaten eradication.

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 accidental exposures and in certain outbreak scenarios. Efforts to discover and develop poliovirus antiviral agents have been ongoing in earnest since the formation in 2007 of the Poliovirus Antivirals Initiative. The most advanced antiviral, pocapavir (V-073), is a capsid inhibitor that has recently demonstrated activity in an oral poliovirus vaccine human challenge model. Additional antiviral candidates with differing mechanisms of action continue to be profiled and evaluated preclinically with the goal of having 2 antivirals available for use in combination to treat iVDPV excreters.

Factors contributing to outbreaks of wild poliovirus type 1 infection involving persons aged ≥15 years in the Democratic Republic of the Congo, 2010-2011, informed by a pre-outbreak poliovirus immunity assessment.

BACKGROUND: The Democratic Republic of the Congo (DRC) experienced atypical outbreaks of wild poliovirus type 1 (WPV1) infection during 2010-2011 in that they affected persons aged ≥15 years in 4 (Bandundu, Bas Congo, Kasaï Occidental, and Kinshasa provinces) of the 6 provinces with outbreaks. METHODS: Analyses of cases of WPV1 infection with onset during 2010-2011 by province, age, polio vaccination status, and sex were conducted. The prevalence of antibodies to poliovirus (PV) types 1, 2, and 3 was assessed in sera collected before the outbreaks from women attending antenatal clinics in 3 of the 4 above-mentioned provinces. RESULTS: Of 193 cases of WPV1 infection during 2010-2011, 32 (17%) occurred in individuals aged ≥15 years. Of these 32 cases, 31 (97%) occurred in individuals aged 16-29 years; 9 (28%) were notified in Bandundu, 17 (53%) were notified in Kinshasa, and 22 (69%) had an unknown polio vaccination status. In the seroprevalence assessment, PV type 1 and 3 seroprevalence was lower among women aged 15-29 years in Bandundu and Kinshasa, compared with those in Kasaï Occidental. Seropositivity to PVs was associated with increasing age, more pregnancies, and a younger age at first pregnancy. CONCLUSIONS: This spatiotemporal analysis strongly suggests that the 2010-2011 outbreaks of WPV1 infection affecting young adults were caused by a PV type 1 immunity gap in Kinshasa and Bandundu due to insufficient exposure to PV type 1 through natural infection or vaccination. Poliovirus immunity gaps in this age group likely persist in DRC.

Infection of human islets of Langerhans with two strains of Coxsackie B virus serotype 1: assessment of virus replication, degree of cell death and induction of genes involved in the innate immunity pathway.

Type 1 diabetes mellitus is believed to be triggered, in part, by one or more environmental factors and human enteroviruses (HEVs) are among the candidates. Therefore, this study has examined whether two strains of HEV may differentially affect the induction of genes involved in pathways leading to the synthesis of islet hormones, chemokines and cytokines in isolated, highly purified, human islets. Isolated, purified human pancreatic islets were infected with strains of Coxsackievirus B1.Viral replication and the degree of CPE/islet dissociation were monitored. The expression of insulin, glucagon, CXCL10, TLR3, IF1H1, CCL5, OAS-1, IFNß, and DDX58 was analyzed. Both strains replicated in islets but only one of strain caused rapid islet dissociation/CPE. Expression of the insulin gene was reduced during infection of islets with either viral strain but the gene encoding glucagon was unaffected. All genes analyzed which are involved in viral sensing and the development of innate immunity were induced by Coxsackie B viruses, with the notable exception of TLR3. There was no qualitative difference in the expression pattern between each strain but the magnitude of the response varied between donors. The lack of virus induced expression of TLR3, together with the differential regulation of IF1H1, OAS1 and IFNß, (each of which has polymorphic variants influence the predisposition to type 1 diabetes), that might result in defective clearance of virus from islet cells. The reduced expression of the insulin gene and the unaffected expression of the gene encoding glucagon by Coxsackie B1 infection is consistent with the preferential ß-cell tropism of the virus.

Anti-poliovirus activity of protease inhibitor AG-7404, and assessment of in vitro activity in combination with antiviral capsid inhibitor compounds.

The National Research Council has recommended that at least one, preferably two, polio antiviral drugs be developed as a supplement to the tools currently available for control of polio outbreaks post-eradication. The primary application of such drugs is expected to be the resolution of chronic poliovirus excretion in persons with primary immunodeficiency disorders. We have assessed the in vitro activity of AG-7404 (also known as "compound 1"), an inhibitor of picornaviral 3C protease, against a large panel of programmatically important poliovirus strains and its activity in combination with two poliovirus capsid inhibitors, V-073 and BTA798. AG-7404 was active against all viruses in this panel, with EC50 values ranging from 0.080 to 0.674 µM. Similarly, BTA798 was active against all viruses in this panel, with EC50 values ranging from 0.003 to 0.591µM. By comparison, values for V-073 were 0.003-0.126 µM. BTA798 was active against V-073-resistant variants with an alanine to valine change in VP3 at position 24. However, BTA798 was inactive against the V-073-resistant strains with amino acid substitutions at VP1 amino acids 194 (equivalent to 192 in type 3) and 236. As expected from its different mechanism of action, AG-7404 was fully active against all V-073-resistant variants, with EC50 values ranging from 0.218 to 0.819 µM, compared to values of 0.202-0.407 µM for the V-073-susceptible parental strains. In vitro drug combination experiments demonstrated synergy between AG-7404 and either V-073 or BTA798, whereas the combination of the two capsid inhibitors acted additively.