別添

Summary Report from the Twenty-fourth
Meeting of the Global Commission for
Certification of Poliomyelitis Eradication

Geneva, Switzerland, 22-23 November 2023

Report from the Twenty-fourth Meeting of the GCC, Geneva, 22 – 23 November 2023

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Members of the Global Commission for Certification of Poliomyelitis
Eradication, Regional and Global Secretariats and GPEI partners

GCC members, left to right, front row: Professor Yagoub Al-Mazrou, Dr Arlene King,
Professor Mahmudur Rahman, Professor David Salisbury, Professor Rose Leke,
Dr Nobuhiko Okabe, photo taken at the 23rd meeting in Amman

Report from the Twenty-fourth Meeting of the GCC, Geneva, 22 – 23 November 2023

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Abbreviations
Containment
CAG
Containment Advisory GroupCC
Certificate of Containment
CCS
Containment Certification Scheme to support GAPIIICP
Certificate of Participation
CWG
Containment Working Group of the GCC
ICCInterim Certificate of Containment
GAPIII
Global Action Plan for Poliovirus Containment, 3rd edition, 2014
NAC
National Authority for Containment
PEF
Poliovirus-Essential Facility
Certification
GCC
Global Commission for Certification of Poliomyelitis Eradication
NCC
National Certification Committee
RCC
Regional Commission for Certification of Poliomyelitis Eradication
AmRCC
RCC of the Americas
AfRCC
African RCC
EMRCC
Eastern Mediterranean RCC
EuRCC
European RCC
SEARCCSouth East Asian RCC
WPRCC
Western Pacific RCC
Viruses and vaccines
IPV
Inactivated poliomyelitis vaccine
OPV
Oral poliomyelitis vaccine
bOPV
Bivalent oral poliomyelitis vaccine containing Sabin type 1 and 3
mOPV2
Monovalent oral poliomyelitis vaccine Sabin type 2
nOPV2
Novel oral poliomyelitis vaccine type 2
PV
Poliovirus (PV1 is PV type 1 etc)
VDPV
Vaccine-derived poliovirusaVDPV
Ambiguous vaccine-derived poliovirus
cVDPV
Circulating vaccine-derived poliovirusiVDPV
Immunodeficiency-associated vaccine-derived poliovirus
WPV
Wild poliovirus
WPV1
Wild poliovirus type 1
WPV2
Wild poliovirus type 2
WPV3
Wild poliovirus type 3
Others
AFP
Acute Flaccid Paralysis
BMGF
Bill and Melinda Gates Foundation
CDC
Centers for Disease Control (United States of America)ES
Environmental surveillance
GPEI
Global Polio Eradication Initiative
IDP
Internally Displaced Persons
IMB
Independent Monitoring Board
KPI
Key Performance Indicator
LQAS
Lot Quality Assurance Sampling
PID
Primary Immunodeficiency Disorders
SAGE
Strategic Advisory Group of Experts on immunization
TAG
Technical Advisory Group
ToR
Terms of Reference
WHO
World Health Organization

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Contents

Introduction ..........................................................................................................................................................4
Aim and Objectives ............................................................................................................................................4
Session 1: Endemic Countries Update ...................................................................................................................5
Session 2: Global Surveillance and Certification...................................................................................................6
Session 3: Feedback from RCCs - current priorities and issues .......................................................................... 10
Session 4: Poliovirus Containment ..................................................................................................................... 13
Annex 1: Agenda ............................................................................................................................................... 17
Annex 2: Final Version of the Principles for Certification of Elimination of cVDPV..................................... 18

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Introduction
The 24th meeting of the Global Commission for Certification of Poliomyelitis
Eradication (GCC) took place in Geneva on 22 – 23 November 2023, chaired byProfessor David Salisbury. Commission Members are chairs of their respective
Regional Commissions for Certification of Poliomyelitis Eradication (RCC):
Professor David Salisbury – WHO European Region,
Professor Yagob Al-Mazrou – WHO Eastern Mediterranean Region,
Dr Arlene King – WHO Region of the Americas, and Chair, GCC Containment Working Group,
Dr Nobuhiko Okabe - WHO Western Pacific Region,
Professor Mahmudur Rahman – WHO South-East Asian Region.
Professor Rose Leke Chair of the WHO African Region Certification Commission was
unable to attend.

Aim and Objectives
The aim of the meeting was to ensure global certification of poliovirus eradication
takes place in a timely manner with transparent processes.
The main objectives of the GCC meeting were:•To review progress towards eradication of WPV, including the response to theoutbreak of WPV1 in south-eastern Africa;•

To review progress towards stopping and preventing outbreaks of cVPDV2;•

To make recommendations regarding the criteria for certification of eliminationof cVDPVs;•

To review progress on containment of polioviruses, focusing on timelines of PV2
containment in view of ongoing use of type 2 polio vaccines in response tocVDPV2 outbreaks, and make recommendations in this regard, and•To review the outcomes of the mid-term review of the Global Polio Eradication
Strategy 2022-2026, and make recommendations accordingly vis-à-vis
certification of poliomyelitis eradication.

The agenda is included in appendix 1.

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Session 1: Endemic Countries Update
Polio eradication in Afghanistan
The WHO Afghanistan polio team gave a detailed presentation covering:-the current status of polio eradication in Afghanistan,efforts to stopping poliovirus transmission,
surveillance performance and efforts to improve sensitivity,
geographies and populations of concern for surveillance.

In summary, the Afghanistan polio team asserted that the situation represented
the best opportunity ever to stop poliovirus transmission. Intense vaccinationinterventions were conducted to stop transmission in endemic areas and prevent
establishment in the rest of the country. Limitations in SIA modality remains
the key bottleneck to eradication. There is a functional community-based
surveillance system achieving targets of global indicators. The surveillancesystem has inbuilt quality assurance mechanisms, and surveillance audits haveidentified gaps which were being addressed, primarily related to
documentation. Identified areas and populations of concerns were under higher
scrutiny.
Polio eradication in Pakistan
The WHO Pakistan polio team gave a detailed presentation covering:-

the WPV1 epidemiology,
the polio surveillance system,
main challenges,
population immunity to stop transmission.

Endemic transmission (YB3C cluster) remains restricted to south KP, however, theintensity of transmission declined significantly in 2023. Repeated introduction of YB3A
cluster strains has been detected in all provinces of Pakistan. There is evidence of local
transmission of the imported YB3A strains in Karachi and Peshawar. The increased
detection of YB3A strains across Pakistan during the last three months is consistent withknown seasonal population movements and the high poliovirus transmission season. A
massive repatriation of Afghani population from Pakistan increased the risk of further
spread within Pakistan and cross-border
The surveillance system has been strengthened further since the previous GCC meetingin February 2023 - field surveillance and laboratory capacity improved significantly.
Poliovirus transmission has been detected from even remote districts and detection
matches with the recent population movement. The current surveillance system has
the ability to detect even low-level transmission.
The programme has been able to build and maintain high population immunity except
in a few access compromised areas. Maintaining high immunity in these difficult to5

access populations and areas remains a big challenge.
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Session 1 Conclusions

Governance and Structure of the Global Polio Eradication Initiative. Available at: http://polioeradication.
org/who-we-are/governance-and-structure/

Pakistan / Afghanistan

1. GCC appreciates the detailed briefings provided by the Afghanistan and Pakistanpolio teams, facilitated by the Eastern Mediterranean RCC and WHO EMRO.
2. GCC noted the ongoing WPV1 transmission in the endemic zones of Afghanistan andPakistan, the eastern part of Afghanistan and southern Khyber Pakhtunhwa (KP) of
Pakistan, respectively
3. Since quarter 2 of 2023, there is WPV1 spread from endemic zones toepidemiologically important areas like Kandahar in Afghanistan and Peshawar,
Karachi and Quetta Block in Pakistan, detected mainly through environmental
surveillance.
Session 1 Recommendation
Continuing to coordinate closely with the EMRCC concerning the situation in
Afghanistan and Pakistan including surveillance quality, in order that certification
remains high quality and robust.

Session 2: Global Surveillance andCertification
Update on iVDPV Surveillance and bOPV cessation
The GCC received a presentation on iVDPV surveillance from the GPEI working group on
this topic. The aim of the presentation was to inform GCC about current status of iVDPV
surveillance and plans for the future and to align the iVDPV portfolio with GCC’s
strategy on certification of VDPV eradication.
Field implementation of iVDPV surveillance is feasible and works. However “one size
does not fit all” as countries have very different systems of immunology care with some
centralized and others fragmented and the surveillance strategy needs to consider thesedifferences. Sensitivity of surveillance will never be perfect as it is based on sentinelsites, and undetected iVDPV excretors will continue to exist. Setting up surveillancetakes time and requires financing. The highest risk of iVDPV emergence and spread is incountries that use bOPV in RI, have a large population, have PID diagnostic andtreatment capacity allowing PID patients to survive, have low RI coverage permittingiVDPV spread and have a high proportion of consanguine marriages
Regarding bOPV cessation planning, the presentation updated the GCC on planning for
bOPV cessation in order to seek GCC’s guidance on how to validate absence of
persistent cVDPVs which is a pre-requisite for bOPV cessation.

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The risks of failure to control cVDPVs following bOPV cessation are similar to thosefollowing the tOPV-bOPV switch. The main risk is undetected cVDPV1/3 circulation at
the time of cessation. High population immunity for types 1 and 3 before bOPV
cessation is the best prevention against failure and pre-cessation bOPV campaigns must
focus on identified high-risk areas and consequential geographies. Outbreak capacity
including type specific OPV vaccines must be established.

Progress in Implementation of Global Polio Surveillance Action Plan
The GPEI Surveillance Group provided an update, comprising:
Surveillance indicators performance globally shows a system that is moderately
sensitive.
In 2022 and 2023 YTD, 61% of priority countries have >80% of districts with a NPAFP >=2,
which is above the certification target. There has been little change in stool adequacy
from 2022 to 2023 with majority of countries meeting the indicator at the national
level, but heterogeneity in performance at district (Admin 2) level.
Although new laboratory methods such as direct detection are still being piloted,
improvements in logistics and transports of samples decreased the time to detection for
key countries from 2022 to 2023 (YTD):–Somalia 85 days to 48 days
–Madagascar 110 days to 80 days
–DRC 90 days to 74 days
Most priority countries are unable to maintain a sensitive ES network with the majorityof sites with EV detection rates below 50%. ES is a good tool but can only complement
AFP surveillance and cannot be implemented everywhere; ES is limited by:- the type of sewage system,- density of population,- type (high risk) population.
ES is not a population based surveillance system but rather it a "sentinel system" whichshould be used to cover high risk populations where possible. A high number of ES sites
with limited sensitivity is costly and can be misleading through offering false
reassurance. The negative predictive value of many sites is difficult to interpret-nodetected poliovirus does not mean absence of virus. Results from a sensitive site should
be interpreted only for the population it is draining and cannot be extrapolated to thegeneral population. More data is needed to define a high quality ES site and ES system
within a country. EV detection of 50% should be a minimum; 80% EV detection should be
the standard for a sensitive site.

Criteria for Certification of WPV1 & cVDPVs Elimination
The GCC considered the position paper drafted by an expert working group to develop
principles that should be applied to determine when cVDPV transmission has been
eliminated. The paper in addition to discussing the principles also recommended thatterminology be updated, in particular that the term ‘validation of absence’ fordocumenting the end of cVDPVs be replaced with ‘certification of elimination of cVDPV’.
Eradication is the permanent reduction to zero of the worldwide incidence of infection

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caused by a specific pathogen, as a result of deliberate efforts, with no risk ofreintroduction. No further actions are required, although interventions may be required fora buffer or transition period; eradication is permanent, barring release from containment
laboratories maintaining stocks, genetic engineering to recreate the pathogen or other
unforeseen events.
Elimination (or interruption of transmission) is the reduction to zero incidence of infection
caused by a specific pathogen in a defined geographical area, with minimal risk ofreintroduction, as a result of deliberate efforts. Actions to prevent re-establishment oftransmission are required.
Interpretation of the definitions for live polioviruses
In the context of polio, eradication refers to all transmissible polioviruses, including
cessation and eradication of all vaccine, vaccine-like, and vaccine-derived polioviruses(VDPVs). Eradication of VDPV cannot be achieved while OPV is in use, which represents a
key distinction with WPV, for which high OPV coverage is the key to eradication.
Elimination of cVDPVs refers to interruption of circulation / transmission of all VDPV in adefined geographical area i.e. country or Region but does not include the absence of all
OPV-related viruses such as iVDPV. Elimination of cVDPV is achieved by high coverage of
OPV, while poor coverage is the main risk for generating new emergences of cVDPV. It
remains critical therefore that all OPV using countries ensure and maintain high coverage inall areas and high risk groups to eliminate cVDPV, allowing OPV cessation.
Furthermore, the working group proposed the recommended terminology to describe theelimination of cVDPV and eradication of VDPV be used for the status of countries andRegions with regard to WPV. Thus, WPV2 and WPV3 have been eradicated from all Regions
and countries as certified by the GCC; all Regions have eliminated WPV1 except the Eastern
Mediterranean Region.

Principles for Certifying cVDPV Elimination
1. Phases: There are two phases in the certification of eradication of VDPV; the first phasebeing certification of elimination of cVDPVs, the second phase being global certificationof the eradication of all VDPV.
2. Roles and responsibilities: As occurred for WPVs, certification of elimination of cVDPVs
will be determined by each Regional Certification Commission (RCC) based on the criteria
established by the GCC. After all Regions have certified elimination of cVDPV, global
certification of the elimination of cVDPV by the GCC may occur, to be followed bycertification of eradication of all VDPV. The GCC would advise the Director General WHOof the global eradication of the serotype specific PV.
3. OPV Cessation: Because of the risk of new VDPV being generated through use of OPV,
certification will only be considered after all OPV use has ended, including use of OPV for
outbreak response.
4. Sequential process: Certification of elimination of cVDPVs may be a sequential process
for each poliovirus serotype, as it has been for WPV. This means cVDPV2 could be certified
as eliminated at different times than cVDPV1 and cVDPV3.
5. Period of non-detection: The length of time since the last cVDPV detection to be

Report from the Twenty-fourth Meeting of the GCC, Geneva, 22 – 23 November 20238

considered for certification of elimination of cVDPV may vary by poliovirus type and is yet
to be determined, but should be a flexible period not less than two years, taking into
account:• the quality of surveillance in previously infected countries, including the risk in subpopulation groups poorly or not reached by surveillance and/or immunization activities,
and other data such as molecular analysis of the last chains of transmission, theincidence of orphan viruses or other evidence of missed transmission;• the coverage of OPV prior to cessation and the length of time since OPV was last used in
the Region;• the previous use of Sabin versus novel OPV in the Region;• the IPV coverage;• additional data on sub-national population immunity;• risks from neighboring or demographically linked geographies in other Regions (e.g.
active cVDPV outbreaks, continued use of OPV)1;• the length of time since aVDPV was detected in the Region – aVDPV could be expectedsoon after cessation of all OPV use but would be unexpected later in the post cessation
period;• the status of iVDPV surveillance, including the quality/efficiency of regional
mechanisms for identifying iVDPV excreters, maintaining a Regional or the global
inventory and following up, performing risk assessment and mitigating measures toavert the risk of community transmission as well as the availability of treatment such as
antivirals and monoclonal antibodies for identified cases in the Region;• detection of iVDPV of the same serotype does not affect the certification of eliminationof cVDPV.
6. Surveillance and Containment: Certification of elimination of cVDPVs should be
conducted with the same standards of global surveillance and poliovirus containment2 as
the GCC described for WPV (see box 1 above). Respective RCCs and the GCC may consider
additional in-depth review of surveillance quality among high-risk countries, sub-national
geographies and populations while making the decisions on certification.
7. Final Phase: The period between global certification of cVDPV elimination andcertification of eradication of all VDPV cannot yet be determined, principally because theprecise effect of OPV cessation on the prevalence of VDPV especially iVDPV is unknown.

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recent examples of inter-regional spread of cVDPV2 include from Chad to Sudan and Egypt, Somalia to Ethiopia,
Pakistan/Afghanistan to Tajikistan and Ukraine, and spread between Israel, UK, USA and Canada; there have been no recent
events of inter-regional spread of cVDPV1 and cVDPV3
2
There is a need to synchronize containment and certification processes with regard to continued generation of newmaterials for containment. Containment also cannot be finalized until OPV use stops.

9Session 2 Conclusions
1. GCC agreed to maintain receiving regular reports from the iVDPV Working Groupto ensure consistency with the certification criteria for VDPV and the surveillance ofiVDPV.
2. GCC agreed that the processes of annual reporting by NCCs and RCCs would
provide a useful input into the bOPV Cessation process, which aims to exclude withconfidence any persistent transmission of cVDPV1 or cVDPV3
3. GCC endorsed the work of Expert Working Group on cVDPVs and accepted thedraft principles with some amendments to improve clarity in this complex area ofwork. The final GCC approved principles are in annex 2.
Session 2 Recommendation
The GCC recommended that the draft principles be discussed at the Regional level,
and feedback provided on any issues that may arise in application of these principles.

Session 3: Feedback from RCCs - current
priorities and issues
Western Pacific Region
The presentation featured:- Regional Assessment for Risk of Missed Poliovirus Transmission,- Surveillance for Acute Flaccid Paralysis,- Environmental surveillance in the Western Pacific Region in 2023,- Countries with recent outbreaks,- Poliovirus essential facilities (PEF) in the WPR-2023,- Regional Assessment for Risk of Population Immunity, and- Key outcomes of 28th meeting of RCC.

Eastern Mediterranean Region
The presentation featured:- Stopping WPV1 transmission- Stopping all cVDPV outbreaks- Consequential geographies: Somalia and Yemen- Stopping other outbreaks: Egypt, Djibouti, Sudan- Highly sensitive poliovirus surveillance (AFP, ES, iVDPV) supported by a strong regional
lab network to guide interruption of transmission and underpin certification- Risk assessments and mitigation and prevention of outbreaks through strengthening
routine immunization; preparedness for outbreaks, and more integrated campaigns.

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South-east Asian Region
The presentation focussed on the recommendations from the SEARCCPE:
Certification process- Secretariat to continue to make efforts to gather information from DPR Korea and
Myanmar on immunization and surveillance performance and share with SEARCCPE
when available- Secretariat to develop and share guidelines related to membership of NCCPEs with allcountries- NCCPEs continue to meet at least twice in a year
Surveillance- Involve all sectors of health system including NGOs and private sector for reporting AFP
cases- On-site accreditation visits to polio laboratories every three years- Countries with low/decreasing NPEV isolation should investigate the reasons
Population Immunity- Countries that have not yet implemented IPV2 introduction or schedule optimization,
should do so in accordance with SAGE guidance that was approved by the SEAR-ITAG(August 2023)- NCCPEs should closely review the coverage of IPV2 and recommend appropriate actions
based on local context to improve coverage- Targeted immunization program for missed children including outreach efforts forhard-to-reach areas and additional strategies such as risk communication andcommunication message to reduce hesitancy wherever it is present
Containment- Countries with PEFs should prepare exposure response plan and conduct containment
breach exercise
Outbreak Preparedness- Subnational risk assessment and take actions to strengthen immunization andsurveillance systems with a subnational focus- Conduct polio outbreak simulation exercises (POSE) at least once in three years

European Region
The EuRCC noted that the polio outbreaks in the Region were well managed and evidence
suggests transmission has stopped.
Urgent action is needed by all countries to protect against importation of cVDPV2 throughhigh population immunity and strong surveillance, AFP and supplemental.
The EuRCC noted continued gaps in polio containment in the Region and welcomed
additional advocacy with Romania.
RCC expressed concerns about the considerable challenges that remain in Ukraine.

African Region
The Region is on track to meet its Phase I milestone of ending WPV1 and cVDPV1 outbreaks
in Southern Africa, with no new case in more than 12 months.
With the availability of adequate vaccine stockpile for outbreak response, now is the time
to move quickly and end ongoing outbreaks. The Region has been ramping up response tocVDPVs in the second half of 2023 and is focused on ending all ongoing active outbreaks byend of 2024 and addressing any remnant risk in 2025

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Nigeria and the Lake Chad basin countries, and DRC have contributed the highest numberof cases and have been the source of international spread; focus will be on maintainingpressure on the virus through the end of 2023 and accelerating response in early 2024
Madagascar has seen sustained transmission of poliovirus type 1; country has implemented
4 major rounds including subnational rounds targeting all age groups; with the aim ofending transmission all together by end of 2024, response efforts to be maintained nextyear.
Coordinated response in the Horn of Africa to the outbreak in Somalia that has spilled overto Kenya and may further spread to Ethiopia planned.
West African and Southern African countries have seen a resurgence of poliovirus type 2
outbreaks, response to ongoing outbreaks on track; to address risk to other countries inthe sub-region, surveillance and outbreak response preparedness being enhanced.
Poliovirus type 1 risk increasing; population immunity declining; current plans inadequate
to address risk; essential immunization systems strengthening coupled with regularpreventive supplementary immunizations targeting missed cohorts required
Region of the Americas
Vulnerable, hard-to-reach, and vaccine-hesitant populations.
- To identify their interconnections with other similar communities both within the
country and elsewhere.
Vaccination and Surveillance.
- All countries to achieve high vaccination coverage in all districts and strengthen AFP
surveillance.
Detection of the VDPV1 case in Peru.
- Countries and adjacent districts in the Amazonian region to achieve high vaccination
coverage and strengthen surveillance.
TAG and previous RCC recommendations.
Review vaccination against polio and AFP surveillance and continue with theirimplementation.

Session 3 Conclusions
1. The GCC noted the different challenges in the six WHO Regions, and the keyrole of RCCs in documenting and supporting countries in addressing thesechallenges.
2. The GCC concluded that all five certified Regions continue to be free ofindigenous wild polio transmission, recognizing the WPV1 outbreak in southeastern
Africa was due to an importation from Pakistan.
Recommendation
The GCC recommended that all Regions and countries continue to address
surveillance gaps, population immunity, polio outbreak preparedness and planningand poliovirus containment so that the world is in the best possible position tocertify global WPV eradication no later than 2026.

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Session 4: Poliovirus Containment
There has been much progress achieved with implementing the commitments in resolution
WHA 71.16 (2018) Poliomyelitis– Containment of Polioviruses 3 and GCC recommendations over
the years.
As of November 2023, 22 countries host 69 facilities retaining polioviruses:•
Romania and China are the only two countries that have yet to establish a NAC•
42 of the 69 facilities retaining polioviruses have valid GCC-countersigned CPs and are
officially in the CCS•
Four countries, Australia, China, Serbia and Romania have yet to submit CP applications
for their facilities.
•
Four countries, Canada, France, Republic of Korea and USA have progressed to the ICC
phase where five facilities have been awarded a GCC-countersigned ICCs.
Several key containment issues were raised which included:
1.
Need for increased advocacy to reduce the number of facilities retaining polioviruses
globally.
2.
Need for capacity building opportunities to support national stakeholders in performing
their functions, including implementation of containment guidance documents, to beprovided using the most feasible modality.
3.
Need to complete the revision of containment guidance documents as soon as possible,
including GAPIV, CCS and PIM Guidance.
4.
Lack of standardized and globally harmonized reporting and indicators to monitor
progress with implementation of poliovirus survey and inventory activities. Survey andinventories activities are required if WPV or VDPV is in circulation or OPV is in use. Such
activities are resource intensive and do not provide the expected assurance that all PV
materials have been identified and are appropriately managed.
5.
Limited capacity of CWG with an increasing workload associated with the review of CCS
applications.
6.
Challenges of national-level candidate auditors to meet the qualifying requirements tobecome an auditor as described in the CCS. This was addressed by a GCC recommendation in
2021 enabling countries to submit to CWG for prior approval, national ICC plans utilizing incountry auditors with experience and relevant expertise.
The lack of alignment of poliovirus containment timelines with WPV eradication will likely
persist as goals 1 and 2 of the Eradication Strategy 2022 – 2026 4 have been assessed to be offtrack and likely to miss the end-2023 timelines 5 for the interruption of WPV1 transmission
and for the last detection of cVDPV2. The dependence of containment on WPV eradication,
absence of cVDPV2 and cessation of OPV, will also impact the current containment

3

Seventy- First World Health Assembly Resolution WHA 71.16 Poliomyelitis – containment of polioviruses.
Available at: https://apps.who.int/gb/ebwha/pdf_files/WHA71/A71_R16-en.pdf
4Polio Eradication Strategy 2022-2026: Delivering on a Promise. Available at: https://polioeradication.org/gpeistrategy-2022-2026/
5
22nd Report of the Independent Monitoring Board (IMB) and Mid-Term Review: Closing in on Zero. Available
at: https://polioeradication.org/wp-content/uploads/2023/09/22nd-Report-of-The-Independent-MonitoringBoard-IMB.pdf

13requirements6 for the certification of WPV eradication.
Other issues presented include variable data quality associated with surveys and inventories
across the WHO regions; poor and incomplete survey and inventory activities associated withpotentially infectious materials, poliovirus (PV PIM); long-term containment requirements forhandling of novel poliovirus strains and the lack of oversight of facilities retaining PV PIM.

Session 4 Conclusions (Poliovirus Containment Certification)
GCC Conclusions: GCC acknowledged the progress made in containment since the last
meeting as several ICCs have been awarded. GCC noted that the provision of necessary
guidance, tools, and capacity building opportunities to stakeholders to perform theirfunctions is important to ensure sustained progress in poliovirus containment. GCC also noted
the dependence of containment on the WPV eradication milestone and cessation of OPV andthe impact on the current containment requirements for the certification of WPVeradication4.
GCC noted that to meet the containment requirements for the certification of WPVeradication by end -2026, that WPV3, certified eradicated in 2019, and VDPV3, must be
handled/stored in containment effective immediately. Similarly, although not yet
eradicated, WPV1/VDPV1 must be handled/stored in containment in all but endemic
countries effective immediately. The containment requirements for WPV/VDPV of any
serotype are described in the biorisk management standard of the WHO Global Action Plan
for Poliovirus Containment, 4th edition, 2022 (GAPIV)7.
Recommendations:
To ensure sustained poliovirus containment progress, GCC recommends:
4.1 Timelines to meet the containment requirements for the certification of WPVeradication by end-2026 will remain in-place independent of the status of WPV eradication.
4.2 WPV3/VDPV3 holding facilities must apply for an ICC immediately. These facilities are
expected to achieve a Containment Certificate (CC) or an Interim Containment Certificate(ICC) with a clear end-point for obtaining a CC agreed with the CWG / GCC by end-20268.
4.3 Facilities retaining WPV1/VDPV1 in all countries, other than the endemic countries,
must apply for an ICC immediately. These facilities are expected to achieve a Containment
6

Safe and secure containment of WPV retained in facilities, such as laboratories and vaccine manufacturing
facilities - all facilities retaining WPVs should have a Containment Certificate, or an Interim Containment
Certificate, with a clear end-point for obtaining a CC agreed with the GCC. In addition, at the time of global WPV
certification, GCC will consider the status of biorisk management of PIM and readiness to respond to containment
breaches. Report from the Seventeenth Meeting of the GCC, Geneva, Switzerland, 26-27 February 2018. Avalable
at: https://polioeradication.org/wp-content/uploads/2018/04/polio-eradication-certification-17th-meetingglobal-commission-for-certification-of-poliomyelitis-eradication-20180412.pdf
7
WHO-Global-Action-Plan-for-Poliovirus-Containment-GAPIV.pdf (polioeradication.org)
8
Source: Report of the 17th meeting of the Global Commission for the Certification of the Eradication of Poliomyelitis,
26-27 February 2018, Geneva, Switzerland. Available at: https://polioeradication.org/wpcontent/uploads/2018/04/polio-eradication-certification-17th-meeting-global-commission-for-certification-ofpoliomyelitis-eradication-20180412.pdf)

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Certificate (CC) or an Interim Containment Certificate (ICC) with a clear end-point for
obtaining a CC agreed with the CWG / GCC by end-2026.

Session 4 Conclusions (Poliovirus Survey and Inventory)
GCC acknowledges the importance of survey and inventory activities as an important
prerequisite to containment “certification”. GCC also acknowledges the efforts made by the
RCCs and containment regional focal points in ensuring data is collected and made available
in alignment with the qualitative and quantitative indicators previously agreed to by GCC.
However, variability in indicator definitions, data quality and availability still varysignificantly between the different WHO regions.
Recommendations:
4.4 Noting the importance of considering poliovirus survey and inventory completion as aprerequisite to containment certification, GCC recommends that survey and inventory
completion criteria be added to the current containment requirements for WPV eradication
certification and requests that the WHO containment team collaborate with the containment
regional focal points and the RCCs to develop the said criteria. These criteria should beshared with the GCC for approval.
4.5 To ensure a standardized and globally harmonized set of indicators to monitor the
implementation of survey and inventory activities, GCC recommends a revision of thepreviously agreed qualitative and quantitative indicators be carried out by the containment
team at WHO headquarters in collaboration with the containment regional focal points, RCCs
and possibly NCCs and NPCCs to ensure data harmonization across all WHO regions. These
indicators should be shared with the GCC for approval.

Session 4 Conclusions (Containment of Novel Poliovirus Strains and Potentially Infectious
Materials, Poliovirus)
As the global oversight body for poliovirus containment, GCC notes the lack of complianceverification of facilities retaining novel poliovirus strains for specific uses with the terms ofthe ‘temporary waiver’ (‘conditional usage’) as recommended by CAG 9 . GCC notes thatsurvey and inventory activities and collected data for PV IM are more robust and complete
compared to those addressing PV PIM. In addition, GCC notes that currently there is a lack ofan accountability framework for facilities retaining OPV/Sabin PIM against the risk mitigation
strategies described in the PIM Guidance, 2nd edition 2021, and possibly WPV/VDPV PIM
following the revision of the PIM Guidance as per CAG recommendation 5.

9

Sixth meeting of the Poliovirus Containment Advisory Group, 25th, 26th and 27th January 203, Geneva,
Switzerland. Available at: https://polioeradication.org/wp-content/uploads/2023/05/CAG6-Jan-2023-ReportEN-FINAL.pdf

15

Recommendations:
Novel Poliovirus Strains
4.6 GCC reminds all relevant national oversight bodies of reporting requirements offacilities retaining novel poliovirus strains as per the 2022 recommendation 10
4.7 GCC recommends that a mapping exercise be carried out to determine the number andcountry location of facilities (research, manufacturing, etc.) retaining novel poliovirus(nOPV1, nOPV2, nOPV3, tnOPV, S19 (all serotypes with and without N18S), CAVA strains). In
addition, understanding the specific activities being conducted with these strains and the risk
mitigation measures currently in place for their handling novel poliovirus strains in such
facilities will be important to determining an appropriate compliance verification structure.
Potentially Infectious Materials Poliovirus
4.8 GCC recommends that a ‘White Paper’ on the containment of PV PIM be developed withthe aim of presenting evidence on the likelihood of the presence of PV in PV PIM andassessing the risk of a release of poliovirus from facilities retaining PV PIM. This will provide a
better understanding into the level of oversight needed (national or global), the mechanism
for this oversight, and the way forward for the GCC to use these data (if at all) for thecertification of eradication.

10

GCC recommends that WHO maintains an inventory of facilities retaining novel poliovirus strains, with thecollection of the same information as that which is provided in the Certificate of Participation (CP). This
information should be provided by the facility to its National Authority for Containment (NAC) where one exists,or to its National Polio Containment Coordinator and processed onwards to the CWG Secretariat. Report of the
22nd meeting of the Global Commission for the Certification of Eradication of Poliomyelitis, Geneva, Switzerland,
28 - 29 June 2022. Available at: https://polioeradication.org/wp-content/uploads/2022/09/22nd-GCC-report20220907.pdf

Report from the Twenty-fourth Meeting of the GCC, Geneva, 22 – 23 November 2023

16

Annex 1: Meeting Agenda

Global Commission for the Certification of Poliomyelitis Eradication
22 -23 November
DRAFT AGENDA
Wednesday 22 November
Coffee - 10.45
Session 1: ENDEMIC COUNTRIES UPDATE
Aidan O'leary - Director WHO HQ/POLDavid Salisbury

11.00 Opening remarks
11.05
11.50
12.05
12.50

14.15
14.30
15.00
15.30
15.45
16.15
16.30
17.00
17.15

Polio Eradication in Afghanistan (Epidemiology and surveillance – progress, challenges and way forward Dr Mandeep Rathee, WHO/AFG
Discussion
Polio Eradication in Pakistan (Epidemiology and surveillance – progress, challenges and way forward) Dr Zainul A Khan, WHO/PAK
Discussion
13.15 - Lunch
Session 2: Global surveillance and CertificationiVDPV surveillance
Ondrej Mach
Progress in implementation of the GPSAP
Stephanie Kovacs
Update on virology: GPLN Working paper 5
Ousmane Diopoutcomes of the GPEI strategy mid-term assessment
Aidan O'leary
Discussion
Coffee break - 16.00
Report back from cVDPV GCC WG
David Salisbury
Discussion
Draft Recommendations for day 1
GCC members
End
Thursday 23 November

09.00 Review draft recommendations

all
Session 3: Feedback from RCCs - current priorities and issues

09.30
09.50
10.10
10.30

Eastern Mediterranean Update
Western Pacific Update
South East Asian Update
European Region Update

EMRO
WPRO
SEARO
EURO
Coffee break - 10.50

11.10 Region of the Americas Update11.30 African Update including feedback from ARCC WG
12.00 Discussion

PAHO
AFRO

Lunch - 12:30
Session 4: Global Containment
13.30
14.00
14.30
15.00

Global containment progress and gaps
Strategic issues: surveys and inventories; minimum dataset; PIM oversightContainment trajectory: timelines and scope - guidance needed
Discussion
Coffee break - 15.30
16.00 Recommendations from day 2 and wrap up
16.30 End

CNT
CNT
CNT

David Salisbury

17Annex 2: Final Version of the
Principles for Certification of
Elimination of cVDPV

Report from the Twenty-fourth Meeting of the GCC, Geneva, 22 – 23 November 2023

18

GCC Principles for the Global Certification of Eradication of Polio Associated with Vaccine Polioviruses
This document sets out the GCC principles for the certification of eradication of vaccine derived polioviruses after global
cessation of all use of oral poliovirus vaccine (OPV). These principles resulted from discussions by an expert working
group (or working group of polio experts) convened March through October 2023 that were presented to the GCC at its
November 2023 meeting. The principles outlined here have relevance also for the terminology of the certification of wild
polioviruses (annex 1).
Background
The GCC applied the criteria for certification of WPV in Box 1 below in 2015 for global certification of WPV2 eradication 1
and in 2019 for the global certification of WPV3 eradication2, with the exception of full containment of WPV3.
Box 1: Criteria to certify eradication of WPV
1. No WPV transmission detected from any population source1 for the previous three years, and
2. Adequate global poliovirus surveillance2, and
3. Safe and secure containment3 of WPV retained in facilities, such as laboratories and vaccine manufacturing facilities
1

Population sources are humans (both AFP cases and healthy individuals) and environmental sources composing of
human waste-water, and do not include other sources such as laboratories and vaccine manufacturing facilities;
conversely non-population sources include known WPV stocks in facilities. Detection of WPV from a human or theenvironment resulting from a containment breach will not be considered from a population source, unless there issustained transmission in the surrounding population.
2

Adequate global surveillance is defined as:
AFP surveillance that meets the minimum standard of non-polio AFP rate in the under 15 population of ≥ 1 per 100,000
with a stool adequacy of ≥ 80% (collected within 14 days of onset and arriving in good condition), and- clear evidence of a sufficiently well-functioning surveillance system in all high-risk areas and special populationsof-concern to detect transmission, as determined by additional surveillance indicators, or- in countries with strong healthcare systems, with evidence of high population immunity for all poliovirus
serotypes; presence of a national surveillance system capable of detecting poliovirus including through the use notifiabledisease surveillance, or supplemental surveillance systems such as environmental and enterovirus surveillance, shall bedeemed adequate.
3

All facilities retaining WPVs should have a Containment Certificate (CC), or an Interim Containment Certificate (ICC),
with a clear end-point for obtaining a CC agreed with the GCC. In addition, at the time of global WPV certification, theGCC will consider the status of bio-risk management of potentially infectious materials and readiness to respond tocontainment breaches.
Discussing type 1 WPV (WPV1) at its twenty-second meeting in February 2023, the GCC recommended the change in the
period of non-detection in Box 2.
Box 2: Amended criterion on the period of non-detection for WPV1
No WPV transmission detected from any population source for a flexible period, but not less than two years, taking into
account the quality of surveillance in endemic countries, the risk in sub-population groups poorly or not reached bysurveillance, and other data such as molecular analysis of the last chains of transmission.

1

https://polioeradication.org/wp-content/uploads/2016/07/1Report.pdf,
https://polioeradication.org/wp-content/uploads/2016/07/20th-meeting-of-the-Global-Commission-for-the-Certification-ofEradication-of-Poliomyelitis-17-18-October-2019.pdf
2

WHO Definitions3
Eradication is the permanent reduction to zero of the worldwide incidence of infection caused by a specificpathogen, as a result of deliberate efforts, with no risk of reintroduction. No further actions are required,although interventions may be required for a buffer or transition period; eradication is permanent, barring
release from containment laboratories maintaining stocks, genetic engineering to recreate the pathogen orother unforeseen events.
Elimination (or interruption of transmission) is the reduction to zero incidence of infection caused by a specificpathogen in a defined geographical area, with minimal risk of reintroduction, as a result of deliberate efforts.
Actions to prevent re-establishment of transmission are required.
Certification implies a high degree of certainty that specific criteria have been met; requires strict procedures(e.g. documentation process by every country, oversight and vetting by regions, and then oversight and vetting
globally), which could provide high confidence that transmission has stopped.
Interpretation of the definitions for live polioviruses
In the context of polio, eradication refers to all transmissible polioviruses, including eradication of all vaccine,
vaccine-like, and vaccine-derived polioviruses (VDPVs) and cessation of use of all OPV vaccines including bOPV
and novel OPV. Eradication of VDPV cannot be achieved while any OPV is in use, which represents a key
distinction with WPV, for which high OPV coverage is the key to eradication.
Elimination of cVDPVs refers to interruption of transmission of all cVDPV in a defined geographical area, butdoes not include the absence of all OPV-related viruses. Elimination of cVDPV is achieved by high coverage of
OPV, while poor coverage is the main risk for generating new emergences of cVDPV. It remains critical therefore
that all OPV using countries ensure and maintain high coverage in all areas and high risk groups to eliminatecVDPV, allowing OPV cessation.
Although the GCC previously discussed the concept of the validation of absence for documenting the end of
cVDPVs, the GCC agreed that the terminology was not useful and that the GCC, RCCs and GPEI should use theterm ‘certification.’
Polio epidemiology as of October 2023
Since global withdrawal of OPV2 from routine immunization in 2016, cVDPV2 transmission has been detected in
52 countries and caused over 3100 cases of paralysis (as of Oct 2023). OPV2 used for outbreak response has led
to emergence of new cVDPV2 strains responsible for the majority of these paralytic polio cases. The risk ofseeding new VDPVs appears to be lower with nOPV2 use than with Sabin OPV2 use, based on experience withemergences of nOPV2 origin cVDPV2 outbreaks to date, although the same issues of low coverage and thenature of OPV have led to reported cases of cVDPVs caused by nOPV2. The number of unique VDPV detections
and emergences according to poliovirus type and classification is given in table 1 below. In 2023, all firstdetections of VDPV2 have nt changes less than or equal to 13, indicating less than two years since emergence,
assuming a rate of 10 nt changes per year (see annex 2).

3

Global Framework for Multi-disease Elimination (unpublished) accessed 12 October 2023 athttps://www.who.int/docs/default-source/ntds/leprosy/global-consultation-on-global-leprosy-strategy-2021-2030/08global-framework-multi-disease-elimination.pdf

Table 1: aVDPV detections, cVDPV emergence groups and iVDPV detections according to serotype since 1 Jan 2017

type 2type 1
type 3
Ambiguous VDPV
350
33
19
cVDPV emergence groups
88
13
3
Immunodeficient VDPV *388* the number of iVDPV is likely underestimated due to limited surveillance, and the case definition refers to AFP
cases only. Data source: GPEI Polio Information System (PolIS), data exported on 24 Oct 2023
Status of OPV2 cessation
Sabin OPV2 was withdrawn globally from routine immunization programmes in April 2016. Currently, OPV2 isonly being used for responding to cVDPV2 outbreaks and cVDPV high-risk events with the special authorizationof the WHO Director General and under stringent vaccine management measures.
The Strategic Advisory Group of Experts on Immunization (SAGE) also recommended flexibility for the use of
only IPV for responding to cVDPV2 outbreaks in IPV exclusive countries (countries using only IPV and no OPV in
their routine immunization) with high level of sanitation. This option, however, is recommended if transmission
is confined to a well-defined population group or geographical area. In 2022 and 2023, United Kingdom, Israeland United States implemented IPV-only responses to cVDPV2.
Status of OPV1 / OPV3 cessation
While elimination of cVDPV1 and cVDPV3 requires high coverage with OPV1 and OPV3, certification ofelimination of cVDPV1 and cVDPV3 will only be considered after the cessation of all live type-1 and type-3 oral
polio vaccines, including bivalent OPV, monovalent OPV1 and OPV3 as well as any novel live OPV1 and OPV3
vaccines (currently under development). Current GPEI strategic plans focus on coordinated bOPV cessation (i.e.
stopping both types 1 and 3 OPV at the same time everywhere), which itself can only occur after the GCC
certifies the eradication of WPV1. The timing of WPV1 eradication and its certification remain uncertain as of
October 2023, and will depend on the timing of regional certification of elimination in the WHO Eastern
Mediterranean Region. If WPV1 transmission is interrupted in 2024, certification of WPV eradication may occur
as early as 2026, allowing for bOPV cessation in 2027 and onwards.
The date and location of the most recent detection and OPV usage in each WHO Region since 2016 (as at
October 2023) is given in table 2 below.
Table 2: most recent cVDPV and OPV use per WHO Region as at October 2023
RegionLast cVDPV2
OPV2 last used
Last cVDPV1
AFR
Ongoing
Ongoing
Ongoing
AMR
USA (20 Oct 2022)
April 2016
None
EMR
Ongoing
Ongoing
YEM (21 Mar 2021)
EUR
ISR (13 May 2023)
TJK (Sept 2021)
None
SEAR
INO (23 Feb 2023)
INO (May 2023)
MMR (21 Aug 2019)
WPR
PHP (16 Jan 2020)
PHP (May 2020)
MYS (13 Mar 2020)

Last cVDPV3
None
None
OPt (15 Mar 2022)
ISR (16 May 2022)
None
China (25 Feb 2021)

bOPV use
Ongoing
Ongoing
Ongoing
Ongoing
Ongoing
OngoingPrinciples for Certifying cVDPV Elimination
1. Phases: There are two phases in the certification of eradication of VDPV; the first phase being certification ofelimination of cVDPVs, the second phase being global certification of the eradication of all VDPV.
2. Roles and responsibilities: As occurred for WPVs, certification of elimination of cVDPVs will be determined byeach Regional Certification Commission (RCC) based on the criteria established by the GCC. After all Regions
have certified elimination of cVDPV, global certification of the elimination of cVDPV by the GCC may occur, to befollowed by certification of eradication of all VDPV. The GCC would advise the Director General WHO of the
global eradication of the serotype specific PV.
3. OPV Cessation: Because of the risk of new VDPV being generated through use of OPV, certification of cVDPV
elimination and subsequently eradication of VDPV will only be considered after all OPV use has ended, including
use of OPV for outbreak response.
4. Sequential process: Certification of elimination of cVDPVs may be a sequential process for each poliovirus
serotype, as it has been for WPV. This means cVDPV2 could be certified as eliminated at different times thancVDPV1 and cVDPV3.
5. Period of non-detection: The length of time since the last cVDPV detection to be considered for certificationof elimination of cVDPV may vary by poliovirus type and is yet to be determined, but should be a flexible periodof not less than two years, taking into account:












4

the quality of surveillance in previously infected countries, including the risk in sub-population groups poorly
or not reached by surveillance and/or immunization activities, and other data such as molecular analysis of
the last chains of transmission, the incidence of orphan viruses or other evidence of missed transmission
the coverage of OPV prior to cessation and the length of time since OPV was last used in the Region;
the previous use of Sabin versus novel OPV in the Region;
the IPV coverage;
additional data on sub-national population immunity;
risks from neighboring or demographically linked geographies in other Regions (e.g. active cVDPV outbreaks,
continued use of OPV)4;
the length of time since aVDPV was detected in the Region – aVDPV could be expected soon after cessationof all OPV use but would be unexpected later in the post--cessation period;
the status of iVDPV surveillance, including the quality/efficiency of regional mechanisms for identifying
iVDPV excreters, maintaining a Regional or the global inventory and following up, performing risk
assessment and mitigating measures to avert the risk of community transmission as well as the availability oftreatment such as antivirals and monoclonal antibodies for identified cases in the Region;
detection of iVDPV of the same serotype does not affect the certification of elimination of cVDPV.

recent examples of inter-regional spread of cVDPV2 include from Chad to Sudan and Egypt, Somalia to Ethiopia,
Pakistan/Afghanistan to Tajikistan and Ukraine, and spread between Israel, UK, USA and Canada; there have been no recent
events of inter-regional spread of cVDPV1 and cVDPV3

6. Surveillance and Containment: Certification of elimination of cVDPVs should be conducted with the same
standards of global surveillance and poliovirus containment5 as the GCC described for WPV (see box 1 above).
Respective RCCs and the GCC may consider additional in-depth review of surveillance quality among high-riskcountries, sub-national geographies and populations while making the decisions on certification.
7. Final Phase: The period between global certification of cVDPV elimination and certification of eradication of
all VDPV cannot yet be determined, principally because the precise effect of OPV cessation on the prevalence of
VDPV especially iVDPV is unknown.
Pending Issues
Detection of cVDPV in a certified region indicates either: a new emergence, or an importation event, or missed transmission of a pre-certification emergence group, or seeding of a cVDPV outbreak from an infectious iVDPV carrier.
Response protocols for responding to cVDPV in certified regions will need to be developed according to thesource, as well as criteria for determining that a region is no longer certified due to either evidence of missedtransmission, reintroduction of OPV use and/or reestablished transmission of a cVDPV for a period of more than
12 months.
For example, the ideal scenario could be that current cVDPV2 outbreaks end, allowing cessation of use of novel
OPV2 for outbreak use, and after an appropriate amount of time (to be determined) after the last cVDPV2 isdetected in each Region, that Region is certified as having eliminated cVDPV2. Similarly, after a period of nondetection of cVDPV1 and cVDPV3 and OPV cessation, Regions could be certified as having eliminated cVDPV1
and cVDPV3. Deviation from this ideal scenario could occur, with the epidemiology at the time dictating
application of these principles for certification.
Figure 1: The ideal scenario (no time scale) TO BE REVISED

5

There is a need to synchronize containment and certification processes with regard to continued generation of newmaterials for containment. Containment also cannot be finalized until OPV use stops.

Application of ‘Elimination’ and ‘Eradication’ terminology to WPVs.
At present, there is a mixture of terms used by Regions to define their current poliovirus status for WPVs and
VDPVs. Because WPV2 and 3 have been certified as eradicated by GCC, by definition, each Region can define
those viruses as eradicated although their responsibilities had been to report confirmation of interruption oftransmission i.e. elimination to GCC. As a consequence, Regions have used terminology such as being ‘polio-free’with respect to all three wild poliovirus types, except for the EMR and WPV1. Being ‘polio-free’ is confusing
when there has been an importation with limited transmission (AFR in 2021 – 22), and if there has beentransmission, the use of the term ‘indigenous’ can also lack clarity.
It is therefore proposed the recommended terminology to describe the elimination of cVDPV and eradication of
VDPV be used for the status of countries and Regions with regard to WPV. Thus, WPV2 and WPV3 have been
eradicated from all countries as certified by the GCC; all countries have eliminated WPV1 except AFG and PAK.
As an example, Kuwait has been certified as having eradicated WPV2 and WPV3, and as having eliminated WPV1
by the EMRCC. Yemen’s status is the same irrespective of the ongoing transmission of cVDPV2.
This situation becomes more complex when there is consideration of cVDPV. Transmissible polioviruses aredetected and there may be paralysis (US 2022) or transmission with no paralytic cases detected (UK 2022). In
those circumstances, to continue the use of the term ‘polio-free’ may be unhelpful (Region of Americas RCC
Review 2023). For example, in 2023, the Region of the Americas would be categorized as having eliminated
WPV1, eradicated WPV2 and WPV3. No region has yet formally certified the elimination of VDPV – all remain
uncertified.
Polio status in the proposed updated framework:

Virus

Americas

Africa

WPV1
WPV2
WPV3
VDPV1
VDPV2
VDPV3

eliminatedeliminateduncertified
uncertified
uncertified

uncertified
uncertified
uncertified

EasternEuropeanMediterranean
endemic
eliminatedglobally eradicatedglobally eradicateduncertified
uncertified
uncertified
uncertified
uncertified
uncertified

South EastAsia
eliminatedWestern
Pacific
eliminateduncertified
uncertified
uncertified

uncertified
uncertified
uncertified

An appendix to the Principles
For the years 2017 – June 2023 a recent analysis of the period between a new VDPV2 emergence and detection
showed that:• New VDPV2 emergences have a median 8 nt changes when detected.
• cVDPV2s are first detected with more nt changes (median 9) compared with aVDPV2s (median7)• 95% new VDPV2 detections had ≤20 nt changes and 99% were detected with ≤30 nt changes.
• Novel emergences were detected with fewer nt changes (median 7) than Sabin emergences (median 9).
• The upper limit of nt changes has fallen from a peak in 2019 of 64 nt changes to 17 nt changes in 2023
(table 3)• Importantly, assuming a rate of 10 nt changes per year, all novel OPV2 origin emergences were detectedin the WHO African Region within two years (all nt changes ≤13).
Table 3: median and range of nucleotide changes for first detection of VDPV2 viruses 2017 – June 2023

2017

2018

2019

2020

2021

2022

2023

N

23

30

94

69

93

20

26

Median

7

8

8

7

7

7

8

Range

6-38

6-27

6-64

6-32

6-29

6-28

6-17

Table 4: Nucleotide changes* at first detection of cVDPV2 emergence group by region (importations excluded)

AFR(Sabin)AFR(novel)

AMR

EMR

EUR

SEAR

WPR

N

56

8

0

20

1

1

2

Median

10

7

-

7

6

25

39

Range

6-24

6 – 13

-

6-38

6-6

25-25

13-64** The circulating emergence group with 64 nt changes in 2019 was PHL-NCR-1 in the Philippines. It was the
only emergence group with a first detection of >40 nt changes.

Report from the Seventeenth Meeting of the GCC, Geneva, Switzerland, 26-27 February 2018