Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
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Surveillance to track progress toward polio eradication - Worldwide, 2022-2023
Kishore N , Krow-Lucal E , Diop OM , Jorba J , Avagnan T , Grabovac V , Kfutwah AKW , Johnson T , Joshi S , Sangal L , Sharif S , Wahdan A , Tallis GF , Kovacs SD . MMWR Morb Mortal Wkly Rep 2024 73 (13) 278-285 The reliable and timely detection of poliovirus cases through surveillance for acute flaccid paralysis (AFP), supplemented by environmental surveillance of sewage samples, is a critical component of the polio eradication program. Since 1988, the number of polio cases caused by wild poliovirus (WPV) has declined by >99.9%, and eradication of WPV serotypes 2 and 3 has been certified; only serotype 1 (WPV1) continues to circulate, and transmission remains endemic in Afghanistan and Pakistan. This surveillance update evaluated indicators from AFP surveillance, environmental surveillance for polioviruses, and Global Polio Laboratory Network performance data provided by 28 priority countries for the program during 2022-2023. No WPV1 cases have been detected outside of Afghanistan and Pakistan since August 2022, when an importation into Malawi and Mozambique resulted in an outbreak during 2021-2022. During 2022-2023, among 28 priority countries, 20 (71.4%) met national AFP surveillance indicator targets, and the number of environmental surveillance sites increased. However, low national rates of reported AFP cases in priority countries in 2023 might have resulted from surveillance reporting lags; substantial national and subnational AFP surveillance gaps persist. Maintaining high-quality surveillance is critical to achieving the goal of global polio eradication. Monitoring surveillance indicators is important to identifying gaps and guiding surveillance-strengthening activities, particularly in countries at high risk for poliovirus circulation. |
Molecular and Phenotypic Characterization of a Highly Evolved Type 2 Vaccine-Derived Poliovirus Isolated from Seawater in Brazil, 2014.
Cassemiro KM , Burlandy FM , Barbosa MR , Chen Q , Jorba J , Hachich EM , Sato MI , Burns CC , da Silva EE . PLoS One 2016 11 (3) e0152251 A type 2 vaccine-derived poliovirus (VDPV), differing from the Sabin 2 strain at 8.6% (78/903) of VP1 nucleotide positions, was isolated from seawater collected from a seaport in São Paulo State, Brazil. The P1/capsid region is related to the Sabin 2 strain, but sequences within the 5'-untranslated region and downstream of the P1 region were derived from recombination with other members of Human Enterovirus Species C (HEV-C). The two known attenuating mutations had reverted to wild-type (A481G in the 5'-UTR and Ile143Thr in VP1). The VDPV isolate had lost the temperature sensitive phenotype and had accumulated amino acid substitutions in neutralizing antigenic (NAg) sites 3a and 3b. The date of the initiating OPV dose, estimated from the number of synonymous substitutions in the capsid region, was approximately 8.5 years before seawater sampling, a finding consistent with a long time of virus replication and possible transmission among several individuals. Although no closely related type 2 VDPVs were detected in Brazil or elsewhere, this VDPV was found in an area with a mobile population, where conditions may favor both viral infection and spread. Environmental surveillance serves as an important tool for sensitive and early detection of circulating poliovirus in the final stages of global polio eradication. |
Molecular epidemiology of coxsackievirus A6 associated with outbreaks of hand, foot, and mouth disease in Tianjin, China, in 2013.
Tan X , Li L , Zhang B , Jorba J , Su X , Ji T , Yang D , Lv L , Li J , Xu W . Arch Virol 2015 160 (4) 1097-104 Since 2008, Mainland China has undergone widespread outbreaks of hand, foot, and mouth disease (HFMD). In order to determine the characteristics of epidemics and enteroviruses (EV) associated with HFMD in Tianjin, in northern China, epidemiological and virological data from routine surveillance were collected and analyzed. In Tianjin, a persistent epidemic of HFMD was demonstrated during 2008-2013, involving 102,705 mild, 179 severe, and 16 fatal cases. Overall, 8234 specimens were collected from 7829 HFMD patients for EV detection during 2008-2013. Enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) were the dominant serotypes during 2008-2012, and they were replaced by CV-A6 as the major causative agent in 2013. Phylogenetic analysis based on complete VP1 nucleotide sequences revealed that multiple CV-A6 lineages co-circulated in Tianjin, which grouped together with strains from China and other countries and split into two distinct clusters (clusters 1 and 2). Most Tianjin strains grouped in cluster 1 and were closely related to strains from several eastern and southern provinces of China during 2012 and 2013. Estimates from Bayesian MCMC analysis suggested that multiple lineages had been transmitted silently before the outbreaks at an estimated evolutionary rate of 4.10 × 10(-3) substitutions per site per year without a specific distribution of rate variances among lineages. The sudden outbreak of CV-A6 in Tianjin during 2013 is attributed to indigenous CV-A6 lineages, which were linked to the wide spread of endemic strains around eastern and southern China. |
Progress toward poliomyelitis eradication - Afghanistan, January 2022-June 2023
Bjork A , Akbar IE , Chaudhury S , Wadood MZ , Ather F , Jorba J , Martinez M . MMWR Morb Mortal Wkly Rep 2023 72 (38) 1020-1026 When the Global Polio Eradication Initiative began in 1988, wild poliovirus (WPV) transmission was reported in 125 countries. Since 2017, Afghanistan and Pakistan remain the only countries with uninterrupted endemic WPV type 1 (WPV1) transmission. This report describes activities and progress toward polio eradication in Afghanistan during January 2022-June 2023. Two WPV1 cases were reported during January-December 2022 and five during January-June 2023 (as of August 26), all from three provinces in the southeast and east regions bordering Pakistan. All five 2023 patients had reportedly received ≥16 oral poliovirus vaccine doses. WPV1 was detected in sewage samples from a site in the south region in May 2023 and one in the north region in June 2023, the first detections since February 2021 and March 2020, respectively. Restrictions on house-to-house vaccination limit the effectiveness of vaccination campaigns in parts of the south and northeast regions. Because of population movement, the risk for transmission in Afghanistan and Pakistan will remain if WPV1 circulation continues in either country. Despite operational improvements in vaccination activities, interruption of WPV1 transmission in Afghanistan will require committed, uninterrupted efforts, including ongoing coordination with Pakistan on polio eradication activities, to address vaccination coverage gaps that sustain WPV1 circulation. |
Notes from the field: Circulating vaccine-derived poliovirus type 2 emergences linked to novel oral poliovirus vaccine type 2 use - six African countries, 2021-2023
Davlantes E , Jorba J , Henderson E , Bullard K , Deka MA , Kfutwah A , Martin J , Bessaud M , Shulman LM , Hawes K , Diop OM , Bandyopadhyay AS , Zipursky S , Burns CC . MMWR Morb Mortal Wkly Rep 2023 72 (38) 1041-1042 Circulating vaccine-derived poliovirus (cVDPV) outbreaks can occur when oral poliovirus vaccine strains (most often, Sabin monovalent oral poliovirus vaccine type 2 [mOPV2]) undergo prolonged circulation in undervaccinated populations, resulting in genetic reversion to neurovirulence. A novel type 2 oral poliovirus vaccine (nOPV2) has been developed, which has been shown in clinical trials to be less likely than mOPV2 to revert to paralytic variants and to have limited genetic modifications in initial field use (1–4). Approximately 700 million doses of nOPV2 have been administered worldwide in response to outbreaks of cVDPV type 2 (cVDPV2). cVDPV2 detections originating from nOPV2 use from initial rollout during March 2021–September 7, 2023, are described in this report. |
Progress toward poliomyelitis eradication - Pakistan, January 2022-June 2023
Mbaeyi C , Baig S , Safdar RM , Khan Z , Young H , Jorba J , Wadood ZM , Jafari H , Alam MM , Franka R . MMWR Morb Mortal Wkly Rep 2023 72 (33) 880-885 Since the establishment of the Global Polio Eradication Initiative in 1988, Pakistan remains one of only two countries (along with Afghanistan) with continued endemic transmission of wild poliovirus (WPV). This report describes Pakistan's progress toward polio eradication during January 2022-June 2023. During 2022, Pakistan reported 20 WPV type 1 (WPV1) cases, all of which occurred within a small geographic area encompassing three districts in south Khyber Pakhtunkhwa. As of June 23, only a single WPV1 case from Bannu district in Khyber Pakhtunkhwa province has been reported in 2023, compared with 13 cases during the same period in 2022. In addition, 11 WPV1 isolates have been reported from various environmental surveillance (ES) sewage sampling sites to date in 2023, including in Karachi, the capital of the southern province of Sindh. Substantial gaps remain in the quality of supplementary immunization activities (SIAs), especially in poliovirus reservoir areas. Despite the attenuation and apparently limited geographic scope of poliovirus circulation in Pakistan, the isolation of WPV1 from an ES site in Karachi is cause for concern about the actual geographic limits of transmission. Interrupting WPV1 transmission will require meticulous tracking and sustained innovative efforts to vaccinate children who are regularly missed during SIAs and rapidly responding to any new WPV1 isolations. |
Surveillance to track progress toward poliomyelitis eradication - Worldwide, 2021-2022
Stehling-Ariza T , Wilkinson AL , Diop OM , Jorba J , Asghar H , Avagnan T , Grabovac V , Johnson T , Joshi S , Kfutwah AKW , Sangal L , Sharif S , Wahdan A , Tallis GF , Kovacs SD . MMWR Morb Mortal Wkly Rep 2023 72 (23) 613-620 Since the Global Polio Eradication Initiative (GPEI) was established in 1988, the number of wild poliovirus (WPV) cases has declined by >99.9%, and WPV serotypes 2 and 3 have been declared eradicated (1). By the end of 2022, WPV type 1 (WPV1) transmission remained endemic only in Afghanistan and Pakistan (2,3). However, during 2021-2022, Malawi and Mozambique reported nine WPV1 cases that were genetically linked to Pakistan (4,5), and circulating vaccine-derived poliovirus (cVDPV) outbreaks were detected in 42 countries (6). cVDPVs are oral poliovirus vaccine-derived viruses that can emerge after prolonged circulation in populations with low immunity allowing reversion to neurovirulence and can cause paralysis. Polioviruses are detected primarily through surveillance for acute flaccid paralysis (AFP), and poliovirus is confirmed through stool specimen testing. Environmental surveillance, the systematic sampling of sewage and testing for the presence of poliovirus, supplements AFP surveillance. Both surveillance systems were affected by the COVID-19 pandemic's effects on public health activities during 2020 (7,8) but improved in 2021 (9). This report updates previous reports (7,9) to describe surveillance performance during 2021-2022 in 34 priority countries.* In 2022, a total of 26 (76.5%) priority countries met the two key AFP surveillance performance indicator targets nationally compared with 24 (70.6%) countries in 2021; however, substantial gaps remain in subnational areas. Environmental surveillance expanded to 725 sites in priority countries, a 31.1% increase from the 553 sites reported in 2021. High-quality surveillance is critical to rapidly detect poliovirus transmission and enable prompt poliovirus outbreak response to stop circulation. Frequent monitoring of surveillance guides improvements to achieve progress toward polio eradication. |
Update on wild poliovirus type 1 outbreak - Southeastern Africa, 2021-2022
Davlantes E , Greene SA , Tobolowsky FA , Biya O , Wiesen E , Abebe F , Weldetsadik MB , Eboh VA , Chisema MN , da Conceição Mário B , Tinuga F , Bobo PM , Chigodo CK , Sethy G , Hellström JM , Goundara AM , Burny ME , Mwale JC , Jorba J , Makua KS , Howard W , Seakamela L , Okiror S , Thompson A , Ali A , Samba D , Agbo C , Kabamba L , Kazoka A , Zomahoun DL , Manneh F , Abdelrahim K , Kamugisha C , Umar AS . MMWR Morb Mortal Wkly Rep 2023 72 (15) 391-397 Since the Global Polio Eradication Initiative (GPEI) began in 1988, the number of wild poliovirus (WPV) cases has declined by >99.99%. Five of the six World Health Organization (WHO) regions have been certified free of indigenous WPV, and WPV serotypes 2 and 3 have been declared eradicated globally (1). WPV type 1 (WPV1) remains endemic only in Afghanistan and Pakistan (2,3). Before the outbreak described in this report, WPV1 had not been detected in southeastern Africa since the 1990s, and on August 25, 2020, the WHO African Region was certified free of indigenous WPV (4). On February 16, 2022, WPV1 infection was confirmed in one child living in Malawi, with onset of paralysis on November 19, 2021. Genomic sequence analysis of the isolated poliovirus indicated that it originated in Pakistan (5). Cases were subsequently identified in Mozambique. This report summarizes progress in the outbreak response since the initial report (5). During November 2021-December 2022, nine children and adolescents with paralytic polio caused by WPV1 were identified in southeastern Africa: one in Malawi and eight in Mozambique. Malawi, Mozambique, and three neighboring countries at high risk for WPV1 importation (Tanzania, Zambia, and Zimbabwe) responded by increasing surveillance and organizing up to six rounds of national and subnational polio supplementary immunization activities (SIAs).* Although no cases of paralytic WPV1 infection have been reported in Malawi since November 2021 or in Mozambique since August 2022, undetected transmission might be ongoing because of poliovirus surveillance gaps and testing delays. Efforts to further enhance poliovirus surveillance sensitivity, improve SIA quality, and strengthen routine immunization are needed to ensure that WPV1 transmission has been interrupted within 12 months of the first case, thereby preserving the WHO African Region's WPV-free status. |
Update on Vaccine-Derived Poliovirus Outbreaks - Worldwide, January 2021-December 2022.
Bigouette JP , Henderson E , Traoré MA , Wassilak SGF , Jorba J , Mahoney F , Bolu O , Diop OM , Burns CC . MMWR Morb Mortal Wkly Rep 2023 72 (14) 366-371 Circulating vaccine-derived poliovirus (cVDPV) outbreaks* can occur when oral poliovirus vaccine (OPV, containing one or more Sabin-strain serotypes 1, 2, and 3) strains undergo prolonged circulation in under-vaccinated populations, resulting in genetically reverted neurovirulent virus (1,2). Following declaration of the eradication of wild poliovirus type 2 in 2015 and the global synchronized switch from trivalent OPV (tOPV, containing Sabin-strain types 1, 2, and 3) to bivalent OPV (bOPV, containing types 1 and 3 only) for routine immunization activities(†) in April 2016 (3), cVDPV type 2 (cVDPV2) outbreaks have been reported worldwide (4). During 2016-2020, immunization responses to cVDPV2 outbreaks required use of Sabin-strain monovalent OPV2, but new VDPV2 emergences could occur if campaigns did not reach a sufficiently high proportion of children. Novel oral poliovirus vaccine type 2 (nOPV2), a more genetically stable vaccine than Sabin OPV2, was developed to address the risk for reversion to neurovirulence and became available in 2021. Because of the predominant use of nOPV2 during the reporting period, supply replenishment has frequently been insufficient for prompt response campaigns (5). This report describes global cVDPV outbreaks during January 2021-December 2022 (as of February 14, 2023) and updates previous reports (4). During 2021-2022, there were 88 active cVDPV outbreaks, including 76 (86%) caused by cVDPV2. cVDPV outbreaks affected 46 countries, 17 (37%) of which reported their first post-switch cVDPV2 outbreak. The total number of paralytic cVDPV cases during 2020-2022 decreased by 36%, from 1,117 to 715; however, the proportion of all cVDPV cases that were caused by cVDPV type 1 (cVDPV1) increased from 3% in 2020 to 18% in 2022, including the occurrence of cocirculating cVDPV1 and cVDPV2 outbreaks in two countries. The increased proportion of cVDPV1 cases follows a substantial decrease in global routine immunization coverage and suspension of preventive immunization campaigns during the COVID-19 pandemic (2020-2022) (6); outbreak responses in some countries were also suboptimal. Improving routine immunization coverage, strengthening poliovirus surveillance, and conducting timely and high-quality supplementary immunization activities (SIAs) in response to cVDPV outbreaks are needed to interrupt cVDPV transmission and reach the goal of no cVDPV isolations in 2024. |
Vaccine-derived poliovirus serotype 2 outbreaks and response in the Democratic Republic of the Congo, 2017-2021.
Alleman MM , Jorba J , Riziki Y , Henderson E , Mwehu A , Seakamela L , Howard W , Kadiobo Mbule A , Nsamba RN , Djawe K , Yapi MD , Mengouo MN , Gumede N , Ndoutabe M , Kfutwah AKW , Senouci K , Burns CC . Vaccine 2023 41 Suppl 1 A35-A47 Vaccine-derived polioviruses (VDPVs) can emerge from Sabin strain poliovirus serotypes 1, 2, and 3 contained in oral poliovirus vaccine (OPV) after prolonged person-to-person transmission where population vaccination immunity against polioviruses is suboptimal. VDPVs can cause paralysis indistinguishable from wild polioviruses and outbreaks when community circulation ensues. VDPV serotype 2 outbreaks (cVDPV2) have been documented in The Democratic Republic of the Congo (DRC) since 2005. The nine cVDPV2 outbreaks detected during 2005-2012 were geographically-limited and resulted in 73 paralysis cases. No outbreaks were detected during 2013-2016. During January 1, 2017-December 31, 2021, 19 cVDPV2 outbreaks were detected in DRC. Seventeen of the 19 (including two first detected in Angola) resulted in 235 paralysis cases notified in 84 health zones in 18 of DRC's 26 provinces; no notified paralysis cases were associated with the remaining two outbreaks. The DRC-KAS-3 cVDPV2 outbreak that circulated during 2019-2021, and resulted in 101 paralysis cases in 10 provinces, was the largest recorded in DRC during the reporting period in terms of numbers of paralysis cases and geographic expanse. The 15 outbreaks occurring during 2017-early 2021 were successfully controlled with numerous supplemental immunization activities (SIAs) using monovalent OPV Sabin-strain serotype 2 (mOPV2); however, suboptimal mOPV2 vaccination coverage appears to have seeded the cVDPV2 emergences detected during semester 2, 2018 through 2021. Use of the novel OPV serotype 2 (nOPV2), designed to have greater genetic stability than mOPV2, should help DRC's efforts in controlling the more recent cVDPV2 outbreaks with a much lower risk of further seeding VDPV2 emergence. Improving nOPV2 SIA coverage should decrease the number of SIAs needed to interrupt transmission. DRC needs the support of polio eradication and Essential Immunization (EI) partners to accelerate the country's ongoing initiatives for EI strengthening, introduction of a second dose of inactivated poliovirus vaccine (IPV) to increase protection against paralysis, and improving nOPV2 SIA coverage. |
Assessing country compliance with circulating vaccine-derived poliovirus type 2 outbreak response standard operating procedures: April 2016 to December 2020
Darwar R , Biya O , Greene SA , Jorba J , Al Safadi M , Franka R , Wiesen E , Durry E , Pallansch MA . Vaccine 2023 41 Suppl 1 A25-A34 BACKGROUND: Trivalent oral poliovirus vaccine (tOPV) was globally replaced with bivalent oral poliovirus vaccine (bOPV) in April 2016 ("the switch"). Many outbreaks of paralytic poliomyelitis associated with type 2 circulating vaccine-derived poliovirus (cVDPV2) have been reported since this time. The Global Polio Eradication Initiative (GPEI) developed standard operating procedures (SOPs) to guide countries experiencing cVDPV2 outbreaks to implement timely and effective outbreak response (OBR). To assess the possible role of compliance with SOPs in successfully stopping cVDPV2 outbreaks, we analyzed data on critical timelines in the OBR process. METHODS: Data were collected on all cVDPV2 outbreaks detected for the period April 1, 2016 and December 31, 2020 and all outbreak responses to those outbreaks between April 1, 2016 and December 31, 2021. We conducted secondary data analysis using the GPEI Polio Information System database, records from the Anonymized Institution Poliovirus Laboratory, and meeting minutes of the monovalent OPV2 (mOPV2) Advisory Group. Date of notification of circulating virus was defined as Day 0 for this analysis. Extracted process variables were compared with indicators in the GPEI SOP version 3.1. RESULTS: One hundred and eleven cVDPV2 outbreaks resulting from 67 distinct cVDPV2 emergences were reported during April 1, 2016-December 31, 2020, affecting 34 countries across four World Health Organization Regions. Out of 65 OBRs with the first large-scale campaign (R1) conducted after Day 0, only 12 (18.5%) R1s were conducted by the target of 28 days after Day 0. Of the 89 OBRs with the second large-scale campaign (R2) conducted after Day 0, 30 (33.7%) R2s were conducted by the target of 56 days after Day 0. Twenty-three (31.9%) of the 72 outbreaks with isolates dated after Day 0 were stopped within the 120-day target. CONCLUSION: Since "the switch", delays in OBR implementation were evident in many countries, which may be related to the persistence of cVDPV2 outbreaks >120 days. To achieve timely and effective response, countries should follow GPEI OBR guidelines. |
Genetic and epidemiological description of an outbreak of circulating vaccine-derived polio-virus type 2 (cVDPV2) in Angola, 2019-2020.
Morais A , Morais J , Felix M , Neto Z , Madaleno V , Umar AS , Panda N , Lemma F , Chivale JAL , Cavalcante DG , Davlantes E , Ghiselli M , Espinosa C , Whiteman A , Iber J , Henderson E , Bullard K , Jorba J , Burns CC , Diop O , Gumede N , Seakamela L , Howard W , Frawley A . Vaccine 2023 41 Suppl 1 A48-A57 After six years without any detection of poliomyelitis cases, Angola reported a case of circulating vaccine-derived poliovirus type 2 (cVDPV2) with paralysis onset date of 27 March 2019. Ultimately, 141 cVDPV2 polio cases were reported in all 18 provinces in 2019-2020, with particularly large hotspots in the south-central provinces of Luanda, Cuanza Sul, and Huambo. Most cases were reported from August to December 2019, with a peak of 15 cases in October 2019. These cases were classified into five distinct genetic emergences (emergence groups) and have ties with cases identified in 2017-2018 in the Democratic Republic of Congo. From June 2019 to July 2020, the Angola Ministry of Health and partners conducted 30 supplementary immunization activity (SIA) rounds as part of 10 campaign groups, using monovalent OPV type 2 (mOPV2). There were Sabin 2 vaccine strain detections in the environmental (sewage) samples taken after mOPV2 SIAs in each province. Following the initial response, additional cVDPV2 polio cases occurred in other provinces. However, the national surveillance system did not detect any new cVDPV2 polio cases after 9 February 2020. While reporting subpar indicator performance in epidemiological surveillance, the laboratory and environmental data as of May 2021 strongly suggest that Angola successfully interrupted transmission of cVDPV2 early in 2020. Additionally, the COVID-19 pandemic did not allow a formal Outbreak Response Assessment (OBRA). Improving the sensitivity of the surveillance system and the completeness of AFP case investigations will be vital to promptly detect and interrupt viral transmission if a new case or sewage isolate are identified in Angola or central Africa. |
Molecular evolution and antigenic drift of type 3 iVDPVs excreted from a patient with immunodeficiency in Ningxia, China.
Fan Q , Ma J , Li X , Jorba J , Yuan F , Zhu H , Hu L , Song Y , Wang D , Zhu S , Yan D , Chen H , Xu W , Zhang Y . J Med Virol 2023 95 (1) e28215 A 2.5-year-old pediatric patient with acute flaccid paralysis was diagnosed with primary immunodeficiency (PID) in Ningxia Province, China, in 2011. Twelve consecutive stool specimens were collected from the patient over a period of 10 months (18 February 2011 to 20 November 2011), and 12 immunodeficiency vaccine-derived poliovirus (iVDPV) strains (CHN15017-1 to CHN15017-12) were subsequently isolated. Nucleotide sequencing analysis of the plaque-purified iVDPVs revealed 2%-3.5% VP1-region differences from their parental Sabin 3 strain. Full-length genome sequencing showed they were all Sabin 3/Sabin 1 recombinants, sharing a common 2C-region crossover site, and the two key determinants of attenuation (U472C in the 5' untranslated region and T2493C in the VP1 region) had reverted. Temperature-sensitive experiments demonstrated that the first two iVDPV strains partially retained the temperature-sensitive phenotype's nature, while the subsequent ten iVDPV strains distinctly lost it, possibly associated with increased neurovirulence. Nineteen amino-acid substitutions were detected between 12 iVDPVs and the parental Sabin strain, of which only one (K1419R) was found on the subsequent 10 iVDPV isolates, suggesting this site's potential as a temperature-sensitive determination site. A Bayesian Monte Carlo Markov Chain phylogenetic analysis based on the P1 coding region yielded a mean iVDPV evolutionary rate of 1.02 × 10(-2) total substitutions/site/year, and the initial oral-polio-vaccine dose was presumably administered around June 2009. Our findings provide valuable information regarding the genetic structure, high-temperature growth sensitivity, and antigenic properties of iVDPVs following long-term evolution in a single PID patient, thus augmenting the currently limited knowledge regarding the dynamic changes and evolutionary pathway of iVDPV populations with PID during long-term global replication. |
Nearly Complete Genome Sequences of Type 2 Sabin-Like Polioviruses from Northern Nigerian Poliovirus Surveillance, 2016 to 2018.
Zhao K , Schmidt A , Tang K , Castro CJ , Liu H , Pang H , Chen Q , Baba M , Soji OB , Bukbuk D , Akinola M , Adeniji JA , Marine RL , Ng TFF , Jorba J , Burns CC . Microbiol Resour Announc 2022 12 (1) e0073522 We sequenced 109 type 2 Sabin-like poliovirus isolates that had been collected from acute flaccid paralysis patients or healthy children in Nigeria. Understanding the genetic makeup of these viruses may contribute to polio eradication efforts. |
Progress toward poliomyelitis eradication - Afghanistan, January 2021-September 2022
Mohamed A , Akbar IE , Chaudhury S , Wadood MZ , Ather F , Jorba J , Martinez M . MMWR Morb Mortal Wkly Rep 2022 71 (49) 1541-1546 Afghanistan and Pakistan are the two remaining countries with endemic wild poliovirus type 1 (WPV1) transmission (1). During 2019-2020, these countries reported their highest numbers of WPV1 cases since 2014 and experienced outbreaks of type 2 circulating vaccine-derived poliovirus (cVDPV2) (2-4).* In Afghanistan, the number of WPV1 cases nearly doubled, from 29 in 2019 to 56 in 2020; 308 cVDPV2 cases were reported during 2020. After years of active conflict, the Afghanistan government was fully replaced by the Taliban de facto government on August 15, 2021. This report describes activities and progress toward polio eradication in Afghanistan during January 2021-September 2022 and updates previous reports (3,4). During January-December 2021, four WPV1 and 43 cVDPV2 cases were detected, representing decreases of 93% from 56 cases and 86% from 308 cases, respectively, during 2020. During January-September 2022 (reported as of October 20), two WPV1 cases and zero cVDPV2 cases were detected. Although no supplementary immunization activities (SIAs)(†) occurred during July-October 2021, SIAs resumed during November 2021 in all districts after the political transition, and 3.5-4.5 million previously unreachable persons have been vaccinated since. However, restrictions on how SIAs are conducted are still in place in the critical South Region provinces of Kandahar, Helmand, and Uruzgan. If efforts to vaccinate all children are enhanced and expanded, Afghanistan has an opportunity to interrupt WPV1 transmission during 2023. |
Surveillance to track progress towards polio eradication - worldwide, 2020-2021
Wilkinson AL , Diop OM , Jorba J , Gardner T , Snidera CJ , Ahmed J . Wkly Epidemiol Rec 2022 97 157-168 Less than 99.99% of recorded cases of poliomyelitis have occurred since the Global Polio Eradication Initiative (GPEI) was established in 1988. By the end of 2021, only Afghanistan and Pakistan will still have endemic wild poliovirus (WPV). While Malawi reported a case of wild poliovirus type 1 (WPV1) with paralysis onset in 2021, just over a year after the WHO African Region (AFR) was proclaimed WPV-free, 31 nations reported incidences of circulating vaccine-derived poliovirus (cVDPV) between 2020 and 2021. Monitoring for acute flaccid paralysis (AFP) in people under the age of 15 is the main way to identify poliovirus transmission, and confirmation comes from testing stool samples at WHO-accredited labs. In all WHO regions in 2020, the COVID-19 pandemic had an impact on polio vaccination and surveillance; from January to September 2020, fewer AFP cases were reported, and there was a longer delay between collecting stools and labs receiving them than there had been during the same period in 2019. A significant increase from 2020, when only 23 (53%) of the priority countries attained the national targets for the two key surveillance performance metrics, was shown in 2021. High-performance surveillance is necessary to track the spread of the poliovirus. Gaps in surveillance indicators might be found, improvements could be made, and the overall sensitivity and promptness of poliovirus detection might be enhanced in order to successfully eradicate polio. The collection of adequate stool specimens8 from AFP patients, with a target of 80% adequate stool specimens, and the nonpolio AFP (NPAFP) rate, which is a rate of 2 per 100,000 people aged 15 years and considered sufficiently sensitive for detecting circulating poliovirus, are two key performance indicators used to assess the quality of AFP surveillance. 43 priority nations experiencing or at high risk of poliovirus transmission were the subject of an analysis of surveillance indicators as of 25 March 2022. |
Wastewater Testing and Detection of Poliovirus Type 2 Genetically Linked to Virus Isolated from a Paralytic Polio Case - New York, March 9-October 11, 2022.
Ryerson AB , Lang D , Alazawi MA , Neyra M , Hill DT , St George K , Fuschino M , Lutterloh E , Backenson B , Rulli S , Ruppert PS , Lawler J , McGraw N , Knecht A , Gelman I , Zucker JR , Omoregie E , Kidd S , Sugerman DE , Jorba J , Gerloff N , Ng TFF , Lopez A , Masters NB , Leung J , Burns CC , Routh J , Bialek SR , Oberste MS , Rosenberg ES . MMWR Morb Mortal Wkly Rep 2022 71 (44) 1418-1424 In July 2022, a case of paralytic poliomyelitis resulting from infection with vaccine-derived poliovirus (VDPV) type 2 (VDPV2)(§) was confirmed in an unvaccinated adult resident of Rockland County, New York (1). As of August 10, 2022, poliovirus type 2 (PV2)(¶) genetically linked to this VDPV2 had been detected in wastewater** in Rockland County and neighboring Orange County (1). This report describes the results of additional poliovirus testing of wastewater samples collected during March 9-October 11, 2022, and tested as of October 20, 2022, from 48 sewersheds (the community area served by a wastewater collection system) serving parts of Rockland County and 12 surrounding counties. Among 1,076 wastewater samples collected, 89 (8.3%) from 10 sewersheds tested positive for PV2. As part of a broad epidemiologic investigation, wastewater testing can provide information about where poliovirus might be circulating in a community in which a paralytic case has been identified; however, the most important public health actions for preventing paralytic poliomyelitis in the United States remain ongoing case detection through national acute flaccid myelitis (AFM) surveillance(††) and improving vaccination coverage in undervaccinated communities. Although most persons in the United States are sufficiently immunized, unvaccinated or undervaccinated persons living or working in Kings, Orange, Queens, Rockland, or Sullivan counties, New York should complete the polio vaccination series as soon as possible. |
Progress toward poliomyelitis eradication - Pakistan, January 2021-July 2022
Mbaeyi C , Baig S , Safdar MR , Khan Z , Young H , Jorba J , Wadood ZM , Jafari H , Alam MM , Franka R . MMWR Morb Mortal Wkly Rep 2022 71 (42) 1313-1318 After reporting a single wild poliovirus (WPV) type 1 (WPV1) case in 2021, Pakistan reported 14 cases during April 1-July 31, 2022. Pakistan and Afghanistan are the only countries where endemic WPV transmission has never been interrupted (1). In its current 5-year strategic plan, the Global Polio Eradication Initiative (GPEI) has set a goal of interrupting all WPV1 transmission by the end of 2023 (1-3). The reemergence of WPV cases in Pakistan after 14 months with no case detection has uncovered transmission in southern Khyber Pakhtunkhwa province, the most historically challenging area. This report describes Pakistan's progress toward polio eradication during January 2021-July 2022 and updates previous reports (4,5). As of August 20, 2022, all but one of the 14 WPV1 cases in Pakistan during 2022 have been reported from North Waziristan district in Khyber Pakhtunkhwa. In underimmunized populations, excretion of vaccine virus can, during a period of 12-18 months, lead to reversion to neurovirulence, resulting in circulating vaccine-derived polioviruses (cVDPVs), which can cause paralysis and outbreaks. An outbreak of cVDPV type 2 (cVDPV2), which began in Pakistan in 2019, has been successfully contained; the last case occurred in April 2021 (1,6). Despite program improvements, 400,000-500,000 children continue to be missed during nationwide polio supplementary immunization activities (SIAs),* and recent isolation of poliovirus from sewage samples collected in other provinces suggests wider WPV1 circulation during the ongoing high transmission season. Although vaccination efforts have been recently complicated by months of flooding during the summer of 2022, to successfully interrupt WPV1 transmission in the core reservoirs in southern Khyber Pakhtunkhwa and reach the GPEI goal, emphasis should be placed on further improving microplanning and supervision of SIAs and on systematic tracking and vaccination of persistently missed children in these reservoir areas of Pakistan. |
Spatial analysis of genetic clusters and epidemiologic factors related to wild poliovirus type 1 persistence in Afghanistan and Pakistan.
Mendesid A , Whiteman A , Bullard K , Sharif S , Khurshidid A , Alam MM , Salman M , Fordid V , Blairid T , Burns CC , Ehrhardt D , Jorba J , Hsuid CH . PLoS Glob Public Health 2022 2 (6) e0000251 Following the certification of the World Health Organization Region of Africa as free of serotype 1 wild poliovirus (WPV1) in 2020, Afghanistan and Pakistan represent the last remaining WPV1 reservoirs. As efforts continue in these countries to progress to eradication, there is an opportunity for a deeper understanding of the spatiotemporal characteristics and epidemiological risk factors associated with continual WPV1 circulation in the region. Using poliovirus surveillance data from 2017-2019, we used pairwise comparisons of VP1 nucleotide sequences to illustrate the spatiotemporal WPV1 dispersal to identify key sources and destinations of potentially infected, highly mobile populations. We then predicted the odds of WPV1 detection at the district level using a generalized linear model with structural indicators of health, security, environment, and population demographics. We identified evidence of widespread population mobility based on WPV1 dispersal within and between the countries, and evidence indicating five districts in Afghanistan (Arghandab, Batikot, Bermel, Muhamandara and Nawzad) and four districts in Pakistan (Charsada, Dera Ismail Khan, Killa Abdullah and Khyber) act as cross-border WPV1 circulation reservoirs. We found that the probability of detecting WPV1 in a district increases with each armed conflict event (OR = 1.024, +- 0.008), level of food insecurity (OR = 1.531, +-0.179), and mean degrees Celsius during the months of greatest precipitation (OR = 1.079, +- 0.019). Our results highlight the multidisciplinary complexities contributing to the continued transmission of WPV1 in Afghanistan and Pakistan. We discuss the implications of our results, stressing the value of coordination during this final chapter of the wild polio virus eradication initiative. |
Public health response to a case of paralytic poliomyelitis in an unvaccinated person and detection of poliovirus in wastewater - New York, June-August 2022
Link-Gelles R , Lutterloh E , Schnabel Ruppert P , Backenson PB , St George K , Rosenberg ES , Anderson BJ , Fuschino M , Popowich M , Punjabi C , Souto M , McKay K , Rulli S , Insaf T , Hill D , Kumar J , Gelman I , Jorba J , Ng TFF , Gerloff N , Masters NB , Lopez A , Dooling K , Stokley S , Kidd S , Oberste MS , Routh J . MMWR Morb Mortal Wkly Rep 2022 71 (33) 1065-1068 On July 18, 2022, the New York State Department of Health (NYSDOH) notified CDC of detection of poliovirus type 2 in stool specimens from an unvaccinated immunocompetent young adult from Rockland County, New York, who was experiencing acute flaccid weakness. The patient initially experienced fever, neck stiffness, gastrointestinal symptoms, and limb weakness. The patient was hospitalized with possible acute flaccid myelitis (AFM). Vaccine-derived poliovirus type 2 (VDPV2) was detected in stool specimens obtained on days 11 and 12 after initial symptom onset. To date, related Sabin-like type 2 polioviruses have been detected in wastewater* in the patient's county of residence and in neighboring Orange County up to 25 days before (from samples originally collected for SARS-CoV-2 wastewater monitoring) and 41 days after the patient's symptom onset. The last U.S. case of polio caused by wild poliovirus occurred in 1979, and the World Health Organization Region of the Americas was declared polio-free in 1994. This report describes the second identification of community transmission of poliovirus in the United States since 1979; the previous instance, in 2005, was a type 1 VDPV (1). The occurrence of this case, combined with the identification of poliovirus in wastewater in neighboring Orange County, underscores the importance of maintaining high vaccination coverage to prevent paralytic polio in persons of all ages. |
Genetic characterization of novel oral polio vaccine type 2 viruses during initial use phase under emergency use listing - worldwide, March-October 2021
Martin J , Burns CC , Jorba J , Shulman LM , Macadam A , Klapsa D , Majumdar M , Bullows J , Frolov A , Mate R , Bujaki E , Castro CJ , Bullard K , Konz J , Hawes K , Gauld J , Blake IM , Mercer LD , Kurji F , Voorman A , Diop OM , Oberste MS , Modlin J , Macklin G , Eisenhawer M , Bandyopadhyay AS , Zipursky S . MMWR Morb Mortal Wkly Rep 2022 71 (24) 786-790 The emergence and international spread of neurovirulent circulating vaccine-derived polioviruses (cVDPVs) across multiple countries in Africa and Asia in recent years pose a major challenge to the goal of eradicating all forms of polioviruses. Approximately 90% of all cVDPV outbreaks are caused by the type 2 strain of the Sabin vaccine, an oral live, attenuated vaccine; cVDPV outbreaks typically occur in areas of persistently low immunization coverage (1). A novel type 2 oral poliovirus vaccine (nOPV2), produced by genetic modification of the type 2 Sabin vaccine virus genome (2), was developed and evaluated through phase I and phase II clinical trials during 2017-2019. nOPV2 was demonstrated to be safe and well-tolerated, have noninferior immunogenicity, and have superior genetic stability compared with Sabin monovalent type 2 (as measured by preservation of the primary attenuation site [domain V in the 5' noncoding region] and significantly lower neurovirulence of fecally shed vaccine virus in transgenic mice) (3-5). These findings indicate that nOPV2 could be an important tool in reducing the risk for generating vaccine-derived polioviruses (VDPVs) and the risk for vaccine-associated paralytic poliomyelitis cases. Based on the favorable preclinical and clinical data, and the public health emergency of international concern generated by ongoing endemic wild poliovirus transmission and cVDPV type 2 outbreaks, the World Health Organization authorized nOPV2 for use under the Emergency Use Listing (EUL) pathway in November 2020, allowing for its first use for outbreak response in March 2021 (6). As required by the EUL process, among other EUL obligations, an extensive plan was developed and deployed for obtaining and monitoring nOPV2 isolates detected during acute flaccid paralysis (AFP) surveillance, environmental surveillance, adverse events after immunization surveillance, and targeted surveillance for adverse events of special interest (i.e., prespecified events that have the potential to be causally associated with the vaccine product), during outbreak response, as well as through planned field studies. Under this monitoring framework, data generated from whole-genome sequencing of nOPV2 isolates, alongside other virologic data for isolates from AFP and environmental surveillance systems, are reviewed by the genetic characterization subgroup of an nOPV working group of the Global Polio Eradication Initiative. Global nOPV2 genomic surveillance during March-October 2021 confirmed genetic stability of the primary attenuating site. Sequence data generated through this unprecedented global effort confirm the genetic stability of nOPV2 relative to Sabin 2 and suggest that nOPV2 will be an important tool in the eradication of poliomyelitis. nOPV2 surveillance should continue for the duration of the EUL. |
Progress toward polio eradication - worldwide, January 2020-April 2022
Rachlin A , Patel JC , Burns CC , Jorba J , Tallis G , O'Leary A , Wassilak SGF , Vertefeuille JF . MMWR Morb Mortal Wkly Rep 2022 71 (19) 650-655 In 1988, the World Health Assembly established the Global Polio Eradication Initiative (GPEI). Since then, wild poliovirus (WPV) cases have decreased approximately 99.99%, and WPV types 2 and 3 have been declared eradicated. Only Afghanistan and Pakistan have never interrupted WPV type 1 (WPV1) transmission. This report describes global progress toward polio eradication during January 1, 2020-April 30, 2022, and updates previous reports (1,2). This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.* Five WPV1 cases were reported from Afghanistan and Pakistan in 2021, compared with 140 in 2020. In 2022 (as of May 5), three WPV1 cases had been reported: one from Afghanistan and two from Pakistan. WPV1 genetically linked to virus circulating in Pakistan was identified in Malawi in a child with paralysis onset in November 2021. Circulating vaccine-derived polioviruses (cVDPVs), with neurovirulence and transmissibility similar to that of WPV, emerge in populations with low immunity following prolonged circulation of Sabin strain oral poliovirus vaccine (OPV) (3). During January 2020-April 30, 2022, a total of 1,856 paralytic cVDPV cases were reported globally: 1,113 in 2020 and 688 in 2021, including cases in Afghanistan and Pakistan. In 2022 (as of May 5), 55 cVDPV cases had been reported. Intensified programmatic actions leading to more effective outbreak responses are needed to stop cVDPV transmission. The 2022-2026 GPEI Strategic Plan objective of ending WPV1 transmission by the end of 2023 is attainable (4). However, the risk for children being paralyzed by polio remains until all polioviruses, including WPV and cVDPV, are eradicated. |
Surveillance to Track Progress Toward Polio Eradication - Worldwide, 2020-2021.
Wilkinson AL , Diop OM , Jorba J , Gardner T , Snider CJ , Ahmed J . MMWR Morb Mortal Wkly Rep 2022 71 (15) 538-544 Since the Global Polio Eradication Initiative (GPEI) was established in 1988, the number of reported poliomyelitis cases worldwide has declined by approximately 99.99%. By the end of 2021, wild poliovirus (WPV) remained endemic in only two countries (Pakistan and Afghanistan). However, a WPV type 1 (WPV1) case with paralysis onset in 2021, was reported by Malawi a year after the World Health Organization (WHO) African Region (AFR) was certified as WPV-free and circulating vaccine-derived poliovirus (cVDPV) cases were reported from 31 countries during 2020-2021 (1,2). cVDPVs are oral poliovirus vaccine-derived viruses that can emerge after prolonged circulation in populations with low immunity and cause paralysis. The primary means of detecting poliovirus transmission is through surveillance for acute flaccid paralysis (AFP) among persons aged <15 years, with confirmation through stool specimen testing by WHO-accredited laboratories, supplemented by systematic sampling of sewage and testing for the presence of poliovirus (environmental surveillance). The COVID-19 pandemic caused disruptions in polio vaccination and surveillance activities across WHO regions in 2020; during January-September 2020, the number of reported cases of AFP declined and the interval between stool collection and receipt by laboratories increased compared with the same period in 2019 (3). This report summarizes surveillance performance indicators for 2020 and 2021 in 43 priority countries* and updates previous reports (4). In 2021, a total of 32 (74%) priority countries(†) met two key surveillance performance indicator targets nationally, an improvement from 2020 when only 23 (53%) met both targets; however, substantial national and subnational gaps persist. High-performing poliovirus surveillance is critical to tracking poliovirus transmission. Frequent monitoring of surveillance indicators could help identify gaps, guide improvements, and enhance the overall sensitivity and timelines of poliovirus detection to successfully achieve polio eradication. |
Progress toward poliomyelitis eradication - Afghanistan, January 2020-November 2021
Sadigh KS , Akbar IE , Wadood MZ , Shukla H , Jorba J , Chaudhury S , Martinez M . MMWR Morb Mortal Wkly Rep 2022 71 (3) 85-89 Wild poliovirus types 2 and 3 were declared eradicated in 2015 and 2019, respectively, and, since 2017, transmission of wild poliovirus type 1 (WPV1) has been detected only in Afghanistan and Pakistan. In 2020, these countries reported their highest number of WPV1 cases since 2014 and experienced outbreaks of type 2 circulating vaccine-derived poliovirus (cVDPV2)* (1); in Afghanistan, the number of WPV1 cases reported increased 93%, from 29 in 2019 to 56 in 2020, with 308 cVDPV2 cases reported. This report describes the activities and progress toward polio eradication in Afghanistan during January 2020-November 2021 and updates previous reports (2-4). Despite restrictions imposed by antigovernment elements since 2018, disruption of polio eradication efforts by the COVID-19 pandemic, and civil and political instability, eradication activities have resumed. During January-November 2021, four WPV1 cases and 43 cVDPV2 cases were detected, representing decreases of 93% from 56 and 85% from 281, respectively, during the same period in 2020. After the assumption of nationwide control by the current de facto government of Afghanistan during August 2021, health officials committed to oral poliovirus vaccine (OPV) campaigns nationwide, with the potential to vaccinate approximately 2.5 million children against poliovirus who were previously not accessible for ≥2 years. Although challenges remain, vigorous, sustained polio eradication efforts in Afghanistan could result in substantial progress toward eradication during 2022-2023. |
Update on Vaccine-Derived Poliovirus Outbreaks - Worldwide, January 2020-June 2021.
Alleman MM , Jorba J , Henderson E , Wiesen E , Wassilak SGF , Burns CC . MMWR Morb Mortal Wkly Rep 2021 70 (49) 1691-1699 As of May 1, 2016, use of oral poliovirus vaccine (OPV) type 2 for routine and supplementary immunization activities ceased after a synchronized global switch from trivalent OPV (tOPV; containing Sabin strain types 1, 2, and 3) to bivalent OPV (bOPV; containing Sabin strain types 1 and 3) subsequent to the certified eradication of wild type poliovirus (WPV) type 2 in 2015 (1-3). Circulating vaccine-derived poliovirus (cVDPV) outbreaks* occur when transmission of Sabin strain poliovirus is prolonged in underimmunized populations, allowing viral genetic reversion to neurovirulence, resulting in cases of paralytic polio (1-3). Since the switch, monovalent OPV type 2 (mOPV2, containing Sabin strain type 2) has been used for response to cVDPV type 2 (cVDPV2) outbreaks; tOPV is used if cVDPV2 co-circulates with WPV type 1, and bOPV is used for cVDPV type 1 (cVDPV1) or type 3 (cVDPV3) outbreaks (1-4). In November 2020, the World Health Organization (WHO) Emergency Use Listing procedure authorized limited use of type 2 novel OPV (nOPV2), a vaccine modified to be more genetically stable than the Sabin strain, for cVDPV2 outbreak response (3,5). In October 2021, the Strategic Advisory Group of Experts on Immunization (WHO's principal advisory group) permitted wider use of nOPV2; however, current nOPV2 supply is limited (6). This report updates that of July 2019-February 2020 to describe global cVDPV outbreaks during January 2020-June 2021 (as of November 9, 2021)(†) (3). During this period, there were 44 cVDPV outbreaks of the three serotypes affecting 37 countries. The number of cVDPV2 cases increased from 366 in 2019 to 1,078 in 2020 (7). A goal of the Global Polio Eradication Initiative's (GPEI) 2022-2026 Strategic Plan is to better address the challenges to early CVDPV2 outbreak detection and initiate prompt and high coverage outbreak responses with available type 2 OPV to interrupt transmission by the end of 2023 (8). |
Progress toward poliomyelitis eradication - Pakistan, January 2020-July 2021
Mbaeyi C , Baig S , Khan Z , Young H , Kader M , Jorba J , Safdar MR , Jafari H , Franka R . MMWR Morb Mortal Wkly Rep 2021 70 (39) 1359-1364 When the Global Polio Eradication Initiative began in 1988, wild poliovirus (WPV) transmission was occurring in 125 countries; currently, only WPV type 1 (WPV1) transmission continues, and as of August 2021, WPV1 transmission persists in only two countries (1,2). This report describes Pakistan's progress toward polio eradication during January 2020-July 2021 and updates previous reports (3,4). In 2020, Pakistan reported 84 WPV1 cases, a 43% reduction from 2019; as of August 25, 2021, Pakistan has reported one WPV1 case in 2021. Circulating vaccine-derived poliovirus (cVDPV) emerges as a result of attenuated oral poliovirus vaccine (OPV) virus regaining neurovirulence after prolonged circulation in underimmunized populations and can lead to paralysis. In 2019, 22 cases of cVDPV type 2 (cVDPV2) were reported in Pakistan, 135 cases were reported in 2020, and eight cases have been reported as of August 25, 2021. Because of the COVID-19 pandemic, planned supplementary immunization activities (SIAs)* were suspended during mid-March-June 2020 (3,5). Seven SIAs were implemented during July 2020-July 2021 without substantial decreases in SIA quality. Improving the quality of polio SIAs, vaccinating immigrants from Afghanistan, and implementing changes to enhance program accountability and performance would help the Pakistan polio program achieve its goal of interrupting WPV1 transmission by the end of 2022. |
Surveillance to Track Progress Toward Polio Eradication - Worldwide, 2019-2020.
Tuma JN , Wilkinson AL , Diop OM , Jorba J , Gardner T , Snider CJ , Anand A , Ahmed J . MMWR Morb Mortal Wkly Rep 2021 70 (18) 667-673 When the Global Polio Eradication Initiative (GPEI) was established in 1988, an estimated 350,000 poliomyelitis cases were reported worldwide. In 2020, 140 wild poliovirus (WPV) cases were confirmed, representing a 99.99% reduction since 1988. WPV type 1 transmission remains endemic in only two countries (Pakistan and Afghanistan), but outbreaks of circulating vaccine-derived poliovirus (cVDPV) occurred in 33 countries during 2019-2020 (1,2). Poliovirus transmission is detected primarily through syndromic surveillance for acute flaccid paralysis (AFP) among children aged <15 years, with confirmation by laboratory testing of stool specimens. Environmental surveillance supplements AFP surveillance and plays an increasingly important role in detecting poliovirus transmission. Within 2 weeks of COVID-19 being declared a global pandemic (3), GPEI recommended continuing surveillance activities with caution and paused all polio supplementary immunization activities (4). This report summarizes surveillance performance indicators for 2019 and 2020 in 42 priority countries at high risk for poliovirus transmission and updates previous reports (5). In 2020, 48% of priority countries* in the African Region, 90% in the Eastern Mediterranean Region, and 40% in other regions met AFP surveillance performance indicators nationally. The number of priority countries rose from 40 in 2019 to 42 in 2020.(†) Analysis of 2019-2020 AFP surveillance data from 42 countries at high risk for poliovirus transmission indicates that national and subnational nonpolio AFP rates and stool specimen adequacy declined in many priority countries, particularly in the African Region, suggesting a decline in surveillance sensitivity and quality. The findings in this report can be used to guide improvements to restore a sensitive surveillance system that can track poliovirus transmission and provide evidence of interruption of transmission. |
Progress toward poliomyelitis eradication - Pakistan, January 2019-September 2020
Hsu CH , Rehman MS , Bullard K , Jorba J , Kader M , Young H , Safdar M , Jafari HS , Ehrhardt D . MMWR Morb Mortal Wkly Rep 2020 69 (46) 1748-1752 Pakistan and Afghanistan are the only countries where wild poliovirus type 1 (WPV1) is endemic (1,2). In 2019, Pakistan reported 147 WPV1 cases, approximately 12 times the number reported in 2018. As of September 15, 72 cases had been reported in 2020. Since 2019, WPV1 transmission has also spread from Pakistan's core poliovirus reservoirs (Karachi, Peshawar, and Quetta block) to southern districts of Khyber Pakhtunkhwa (KP), Punjab, and Sindh provinces. Further, an outbreak of circulating vaccine-derived poliovirus type 2 (cVDPV2), first detected in July 2019, has caused 22 paralytic cases in 2019 and 59 as of September 15, 2020, throughout the country. The coronavirus disease 2019 (COVID-19) pandemic has substantially reduced delivery of polio vaccines through essential immunization (formerly routine immunization) and prevented implementation of polio supplementary immunization activities (SIAs)* during March-July 2020. This report describes Pakistan's progress in polio eradication during January 2019-September 2020 and updates previous reports (1,3,4). The Pakistan polio program has reinitiated SIAs and will need large, intensive, high-quality campaigns with strategic use of available oral poliovirus vaccines (OPVs)(†) to control the surge and widespread transmission of WPV1 and cVDPV2. |
A respiratory syncytial virus attachment (G) gene variant associated with more severe disease in infants decreases fusion (F) protein expression which may facilitate immune evasion.
Human S , Hotard AL , Rostad CA , Lee S , McCormick L , Larkin EK , Peret TCT , Jorba J , Lanzone J , Gebretsadik T , Williams JV , Bloodworth M , Stier M , Carroll K , Peebles RS Jr , Anderson LJ , Hartert TV , Moore ML . J Virol 2020 95 (2) This study identified a genotype of RSV associated with increased acute respiratory disease severity in a cohort of term, previously healthy infants. The genotype (2stop+A4G) consists of two components. The A4G component is a prevalent point mutation in the 4(th) position of the gene end transcription termination signal of the G gene of currently circulating RSV strains. The 2stop component is two tandem stop codons at the G gene terminus, preceding the gene end transcription termination signal. To investigate the biological role of these RSV G gene mutations, recombinant RSV strains harboring either a wild type A2 strain G gene (one stop codon preceding a wild type gene end signal), an A4G gene end signal preceded by one stop codon, or the 2stop+A4G virulence-associated combination were generated and characterized. Infection with the rA4G RSV mutant resulted in transcriptional read-through and lower G and fusion (F) protein levels relative to wild type. Addition of a second stop codon preceding the A4G point mutation (2stop+A4G) restored G protein expression but retained lower F protein levels. These data suggest that RSV G and F glycoprotein expression is regulated by transcriptional and translational read-through. Notably, while rA4G and r2stop+A4G RSV were attenuated in cells and in naïve BALB/c mice compared to wild type RSV, the r2stop+A4G RSV was better able to infect BALB/c mice in the presence of pre-existing immunity in comparison to rA4G RSV. Together these factors may contribute to the maintenance and virulence of the 2stop+A4G genotype in currently circulating RSV-A strains.IMPORTANCE Strain-specific differences in respiratory syncytial virus (RSV) isolates are associated with differential pathogenesis in mice. However, the role of RSV genotypes in human infection is incompletely understood. This work demonstrates that one such genotype, 2stop+A4G, present in the RSV attachment (G) gene terminus is associated with greater infant disease severity. The genotype consists of two tandem stop codons preceding an A-to-G point mutation in the 4(th) position of the G gene end transcription termination signal. Virologically, the 2stop+A4G RSV genotype results in reduced levels of the RSV fusion (F) glycoprotein. A recombinant 2stop+A4G RSV was better able to establish infection in the presence of existing RSV immunity compared to a virus harboring the common A4G mutation. These data suggest that regulation of G and F expression has implications for virulence and potentially immune evasion. |
Progress Toward Poliomyelitis Eradication - Afghanistan, January 2019-July 2020.
Martinez M , Akbar IE , Wadood MZ , Shukla H , Jorba J , Ehrhardt D . MMWR Morb Mortal Wkly Rep 2020 69 (40) 1464-1468 Wild poliovirus type 1 (WPV1) transmission is ongoing only in Afghanistan and Pakistan (1). Following a decline in case numbers during 2013-2016, the number of cases in Afghanistan has increased each year during 2017-2020. This report describes polio eradication activities and progress toward polio eradication in Afghanistan during January 2019-July 2020 and updates previous reports (2,3). Since April 2018, insurgent groups have imposed bans on house-to-house vaccination. In September 2019, vaccination campaigns in areas under insurgency control were restarted only at health facilities. In addition, during March-June 2020, all campaigns were paused because of the coronavirus disease 2019 (COVID-19) pandemic. The number of WPV1 cases reported in Afghanistan increased from 21 in 2018 to 29 in 2019. During January-July 2020, 41 WPV1 cases were reported as of August 29, 2020 (compared with 15 during January-July 2019); in addition, 69 cases of circulating vaccine-derived poliovirus type 2 (cVDPV2), and one case of ambiguous vaccine-derived poliovirus type 2 (aVDPV2) (isolates with no evidence of person-to-person transmission or from persons with no known immunodeficiency) were detected. Dialogue with insurgency leaders through nongovernmental and international organizations is ongoing in an effort to recommence house-to-house campaigns, which are essential to stopping WPV1 transmission in Afghanistan. To increase community demand for polio vaccination, additional community health needs should be addressed, and polio vaccination should be integrated with humanitarian services. |
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