Statement following Twenty-Eighth IHR Emergency Committee for Polio

The twenty-eighth meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) on the international spread of poliovirus was convened by the WHO Director-General on 4 May 2021 with Committee members and advisers attending via video conference, supported by the WHO Secretariat. The Emergency Committee reviewed the data on wild poliovirus (WPV1) and circulating vaccine-derived polioviruses (cVDPV). The following IHR States Parties provided an update at the video conference on the current situation in their respective countries: Afghanistan, Kenya, Pakistan, Senegal, South Sudan and Tajikistan.

Wild poliovirus

The Committee noted that the higher incidence of global WPV1 cases seen until about mid-2020 came to a plateau during the second half of 2020. The number of WPV1 cases and proportion of WPV1 positive environmental samples have decreased during the first quarter of 2021. Compared to 42 WPV1 cases as of 21 April 2020, two WPV1 cases have been reported from Pakistan and Afghanistan during the same period in 2021. On environmental surveillance, 14% of the samples collected in 2021 (until 21 April) were positive for WPV1 compared to 49% in 2020 for the same period. WPV1 transmission persists in the two cross-border polio reservoirs, the northern corridor comprising of Peshawar-Khyber region of Pakistan and East Region of Afghanistan and the southern corridor comprising of Quetta Block of Pakistan and South Region of Afghanistan. Transmission is also continuing in Karachi, one of the most persistent polio reservoirs in Pakistan. It is important to note that the current transmission level is particularly low in the northern cross-border corridor with no cases reported in 2021 so far and only 8% positive environmental samples (all from Peshawar, Pakistan) during the first quarter of 2021. The decline in WPV1 transmission intensity can possibly be attributed to several factors, including the intense transmission in 2019-20 leading to some natural population immunity, the ongoing low transmission season for polio and to some extent intensified efforts in Pakistan and accessible areas of Afghanistan. The COVID-19 related border closures and lockdowns coupled with social distancing and hand washing may also have had a role in slowing down the transmission. However, unless the issues of inaccessibility of under-immunized children in southern Afghanistan and barriers to reach missed children in the core reservoirs of Pakistan are addressed, the transmission levels are likely to resurge.

The Committee noted that the current situation provides a good opportunity over the next six months to curb the WPV1 transmission by implementing high quality vaccination activities (supplementary and routine) and fast-track progress towards the global WPV1 eradication. The ongoing inaccessibility for vaccination campaigns in Afghanistan (particularly the South Region) and the vaccination quality gaps in key reservoirs of Pakistan (Karachi and Quetta Block in particular) constitute significant risk for the programme's success in this epidemiological block.

The Committee noted that based on results from sequencing of WPV1, there were further instances of international spread of viruses from Pakistan to Afghanistan. The ongoing frequency of WPV1 international spread between the two countries and the ongoing vulnerability of other countries where routine immunization and polio prevention activities have been adversely affected by the COVID-19 pandemic mean that the risk of international spread remains significant.

Circulating vaccine-derived polioviruses (cVDPV)

The Committee noted with concern that since its last meeting in February 2021, cVDPV2 spread to Senegal and Kenya has been confirmed and a new cVDPV1 outbreak has been reported in Madagascar. Despite an overall decreasing trend in the number of cVDPV2 cases in 2021 so far, a significant number of countries (11) remain infected in the African and Eastern Mediterranean regions during the first quarter of the year. Moreover, the most recent quarterly routine analysis (October to December 2020) performed by the Global Polio Laboratory Network (GPLN) indicates cVDPV2 exportation from:

The Committee noted that a total of 13 cVDPV2 emergences have been detected during the first quarter of 2021. This compares with 36 emergences detected during the year 2020 and 44 in 2019. This reduction may reflect refinement and modification of cVDPV2 outbreaks management aimed at lessening the risk of seeding new emergences.

The Committee noted that the novel OPV2 (nOPV2), after receiving the interim recommendation for use under WHO's Emergency Use Listing procedure (EUL), has been introduced and delivered in two countries (Nigeria and Liberia) with an additional four countries to implement nOPV2 campaigns by the end of May. The Strategic Advisory Group of Experts on immunization (SAGE) has endorsed, in principle, nOPV2 to become the vaccine of choice for response to cVDPV2 outbreaks after review of the initial use period is completed and all requirements for use are met. Further, SAGE endorsed the prioritization framework for type 2 vaccines for cVDPV2 outbreak response and agreed with the phases of the framework [Phase A: Pre-EUL recommendation, preparing for nOPV2 use; Phase B: Initial nOPV2 use under interim EUL recommendation (current phase); Phase C: Wider use of nOPV2 under interim EUL recommendation; Phase D: nOPV2 licensed and pre-qualified]. SAGE will review the findings from the initial use period to issue further recommendations on its wider use once the data on safety and stability have been gathered.

The Committee noted that there are currently 60 million doses of nOPV2 in the stockpile, and it is expected to have an additional 252 million nOPV2 doses by end of the year to support its wider use. In addition, trivalent OPV (tOPV) remains available on the advice of the OPV2 Advisory Group and approval by the WHO Director General for use in countries which have concurrent type 1 and type 2 poliovirus infections co-circulating and is being used in both Pakistan and Afghanistan. There are about 2.5 million doses of tOPV currently available in the stockpile and orders are in place for about 140 million additional doses by December 2021. Monovalent OPV2 (mOPV2) also remains available to be utilized to respond to the cVDPV2 outbreaks on the advice of the OPV2 Advisory Group and the approval of the WHO Director General. Currently, 149 mOPV2 doses are available in the stockpile and orders are in place for additional 175 million doses until December 2021.

The Committee noted that the cVDPV1 outbreaks in Madagascar and Yemen have occurred in areas and population groups of known risk, largely due to persistent sub-optimal routine immunization coverage. The Committee recommended to maintain Malaysia in the list of infected countries (despite more than 13 months since the last cVDPV detection), given the significant impact of the COVID-19 pandemic on the implementation of outbreak response.

COVID-19

The Committee noted with concern that many of the polio affected countries are currently experiencing a second wave of COVID-19 with substantial numbers of COVID-19 cases, notably Iran, Kenya, Nigeria and Pakistan. In fact, all the current polio-infected countries are currently classified to have "community transmission", except Sudan and Tajikistan.

Based on the updated GPEI guidance, the polio vaccination campaigns have mostly been resumed by virtue of good coordination among the polio eradication and COVID-19 management structures and coordination entities. The planning and implementation of polio vaccination campaigns is based on carefully performed risk-benefit analysis, utilizing the WHO's decision-making framework and GPEI's operational guidance, with major consideration for the safety of frontline workers and the communities they serve. As the waves of COVID-19 are expected to fluctuate considerably from country to country and across the WHO Regions, the Committee stressed the need to continue making necessary adjustments according to the COVID-19 situation for the foreseeable future.

The surveillance sensitivity and quality are approaching close to the pre-COVID-19 levels, after an initial significant impact of COVID-19 during the second and third quarter of 2020. The Committee noted with concern that ongoing specimen and laboratory challenges are resulting in slow shipment, handling and reporting of samples for polio testing in some countries.

The Committee noted that the polio-funded staff and assets continue to support the pandemic response in more than 50 countries. In view of the overwhelming public health imperative to end the COVID-19 pandemic, the Polio Oversight Board has committed to the polio programme's continued support for the next phase of COVID-19 response, COVID-19 vaccine introduction and delivery, through existing assets, infrastructure and expertise in key geographies.

Conclusion

The Committee unanimously agreed that the risk of international spread of poliovirus remains a Public Health Emergency of International Concern (PHEIC) and recommended the extension of Temporary Recommendations for a further three months. The Committee recognizes the concerns regarding the lengthy duration of the polio PHEIC, but concludes that the current situation is extraordinary, with clear ongoing substantial risk of international spread and utmost need for coordinated international response. The Committee considered the following factors in reaching this conclusion:

Continued risk of WPV1 international spread

Based on the following factors, the risk of international spread of WPV1 appears to be currently very high:

• Despite the reported drop in the number of WPV-1 cases, there is geographically widespread transmission in Pakistan and Afghanistan as evidenced by positive environmental samples.
• Isolation of long chain viruses in both countries indicates the possibility of missed transmission in the hard-to-reach population groups.
• The ongoing inaccessibility in many provinces of Afghanistan has led to the increase in size of highly susceptible populations which continues to drive higher transmission; to date about three million children were missed during all the nation-wide rounds in 2020 and 2021 (the highest in southern Afghanistan), and the cohort of missed children continues to rapidly grow (https://polioeradication.org/wp-content/uploads/2021/05/Afghanistan_NEAP_2021.pdf).
• Inconsistent vaccination campaigns quality in critical areas of Pakistan and Afghanistan, including Karachi, Quetta Block and accessible areas of southern Afghanistan.
• Ongoing barriers to reach missed children in the core reservoirs of Pakistan and Afghanistan, including refusals to polio vaccination.
• The complicated context of WPV eradication activities in Afghanistan and Pakistan created by the need to simultaneously respond to cVDPV2 and COVID-19.
• The second wave of COVID-19 that appears to be currently underway in Pakistan, Afghanistan and many polio-affected countries, making the interventions more complex and difficult.

Rising risk of cVDPV2 international spread:

Based on the following factors, the risk of international spread of cVDPV2 appears to be currently very high:

• Despite the reported decline in the number of cVDPV2 cases, the risk of international spread of cVDPV2 remains quite high as evidenced by recent importation in Senegal (never infected before) and Kenya (re-importation from Somalia).
• The most updated analyses performed by the GPLN on international spread (Oct – Dec 2020), indicates cVDPV2 exportation from one country to another on 17 occasions.
• The cVDPV2 transmission in Afghanistan has spread to areas that have been inaccessible for vaccination campaigns due to local bans for more than two years. This appears to be driving the intense transmission there, with continued high risk of national and international spread.
• The ever-widening gap in population intestinal mucosal immunity in young children since the withdrawal of OPV2 in 2016.
• The same factors regarding the COVID-19 pandemic as mentioned above.

Other factors include:

• Weak routine immunization: Many countries have weak immunization systems that are further impacted by various humanitarian emergencies including the evolving COVID-19 pandemic. The number of countries in which immunization systems have been weakened or disrupted by conflict and complex emergencies poses a growing risk, leaving populations in these fragile states vulnerable to outbreaks of polio.
• Lack of access: Inaccessibility and volatile situations continue to constitute a major risk, particularly in several countries currently infected with WPV1 or cVDPV, i.e. Afghanistan, Nigeria, Niger, Somalia, Yemen, Central African Republic, Mali and South Sudan. All these countries have sizable populations that have been unreached or inconsistently reached with polio vaccine for prolonged periods.
• Population movement: While border closures resulting from COVID-19 prevention measures may have mitigated the short-term risk, conversely the risk once borders begin to re-open is likely to be higher.

  Risk categories

  The Committee provided the Director-General with the following advice aimed at reducing the risk of international spread of WPV1 and cVDPVs, based on the risk stratification as follows:

  1. States infected with WPV1, cVDPV1 or cVDPV3.
  2. States infected with cVDPV2, with or without evidence of local transmission;
  3. States no longer infected by WPV1 or cVDPV, but which remain vulnerable to re-infection by WPV or cVDPV.

Criteria to assess States as no longer infected by WPV1 or cVDPV:

• Poliovirus Case: 12 months after the onset date of the most recent case PLUS one month to account for case detection, investigation, laboratory testing and reporting period OR when all reported AFP cases with onset within 12 months of last case have been tested for polio and excluded for WPV1 or cVDPV, and environmental or other samples collected within 12 months of the last case have also tested negative, whichever is the longer.
• Environmental or other isolation of WPV1 or cVDPV (no poliovirus case): 12 months after collection of the most recent positive environmental or other sample (such as from a healthy child) PLUS one month to account for the laboratory testing and reporting period

These criteria may be varied for the endemic countries, where more rigorous assessment is needed in reference to surveillance gaps.

Once a country meets these criteria as no longer infected, the country will be considered vulnerable for a further 12 months. After this period, the country will no longer be subject to Temporary Recommendations, unless the Committee has concerns based on the final report.

TEMPORARY RECOMMENDATIONS

States infected with WPV1, cVDPV1 or cVDPV3 with potential risk of international spread

WPV1

cVDPV1

These countries should:

• Officially declare, if not already done, at the level of head of state or government, that the interruption of poliovirus transmission is a national public health emergency and implement all required measures to support polio eradication; where such declaration has already been made, this emergency status should be maintained as long as the response is required.
• Ensure that all residents and long­term visitors (i.e. > four weeks) of all ages, receive a dose of bivalent oral poliovirus vaccine (bOPV) or inactivated poliovirus vaccine (IPV) between four weeks and 12 months prior to international travel.
• Ensure that those undertaking urgent travel (i.e. within four weeks), who have not received a dose of bOPV or IPV in the previous four weeks to 12 months, receive a dose of polio vaccine at least by the time of departure as this will still provide benefit, particularly for frequent travelers.
• Ensure that such travelers are provided with an International Certificate of Vaccination or Prophylaxis in the form specified in Annex 6 of the IHR to record their polio vaccination and serve as proof of vaccination.
• Restrict at the point of departure the international travel of any resident lacking documentation of appropriate polio vaccination. These recommendations apply to international travelers from all points of departure, irrespective of the means of conveyance (e.g. road, air, sea).
• Further intensify cross­border efforts by significantly improving coordination at the national, regional and local levels to substantially increase vaccination coverage of travelers crossing the border and of high risk cross­border populations. Improved coordination of cross­border efforts should include closer supervision and monitoring of the quality of vaccination at border transit points, as well as tracking of the proportion of travelers that are identified as unvaccinated after they have crossed the border.
• Further intensify efforts to increase routine immunization coverage, including sharing coverage data, as high routine immunization coverage is an essential element of the polio eradication strategy, particularly as the world moves closer to eradication.
• Maintain these measures until the following criteria have been met: (i) at least six months have passed without new infections and (ii) there is documentation of full application of high quality eradication activities in all infected and high risk areas; in the absence of such documentation these measures should be maintained until the state meets the above assessment criteria for being no longer infected.
• Provide to the Director-General a regular report on the implementation of the Temporary Recommendations on international travel.

States infected with cVDPV2, with or without evidence of local transmission:

• Officially declare, if not already done, at the level of head of state or government, that the prevention or interruption of poliovirus transmission is a national public health emergency.
• Undertake urgent and intensive investigations to determine if there has been local transmission of the imported cVDPV2.
• Noting the existence of a separate mechanism for responding to type 2 poliovirus infections, consider requesting vaccines from the global mOPV2 stockpile based on the recommendations of the Advisory Group on mOPV2.
• The Priority for countries experiencing cVDPV2 outbreaks should be to conduct high quality outbreak response without delay, with whichever oral polio vaccine is available to them. Noting that WHO has issued an Emergency Use Listing (EUL) recommendation for the type 2 novel oral polio vaccine (nOPV2), all countries at risk of cVDPV2 outbreaks should expedite preparations to meet the criteria for use of nOPV2 and to complete a readiness assessment.
• Further intensify efforts to increase IPV immunization coverage amongst zero dose communities.

Intensify national and international surveillance regional cooperation and cross­border coordination to enhance surveillance for prompt detection of poliovirus.

States with local transmission of cVDPV2, with risk of international spread should in addition to the above measures should:

• Encourage residents and long­term visitors to receive a dose of IPV four weeks to 12 months prior to international travel.
• Ensure that travelers who receive such vaccination have access to an appropriate document to record their polio vaccination status.
• Intensify regional cooperation and cross­border coordination to enhance surveillance for prompt detection of poliovirus, and vaccinate refugees, travelers and cross­border populations, according to the advice of the Advisory Group.

  For both sub-categories:

  • Maintain these measures until the following criteria have been met: (i) at least six months have passed without the detection of circulation of VDPV2 in the country from any source, and (ii) there is documentation of full application of high quality eradication activities in all infected and high risk areas; in the absence of such documentation these measures should be maintained until the state meets the criteria of a 'state no longer infected'.
  • At the end of 12 months without evidence of transmission, provide a report to the Director-General on measures taken to implement the Temporary Recommendations.

States no longer infected by WPV1 or cVDPV, but which remain vulnerable to re-infection by WPV or cVDPV

WPV1

none

cVDPV

Angola (most recent cVDPV2 detection 09 February 2020)

China (most recent cVDPV2 detection 18 August 2019)

Myanmar (most recent cVDPV1 detection 21 August 2019)

Philippines (most recent cVDPV1 detection 16 January 2020)

Zambia (most recent cVDPV2 detection 25 November 2019)

These countries should:

• Urgently strengthen routine immunization to boost population immunity.
• Enhance surveillance quality, including considering introducing supplementary methods such as environmental surveillance, to reduce the risk of undetected WPV1 and cVDPV transmission, particularly among high risk mobile and vulnerable populations.
• Intensify efforts to ensure vaccination of mobile and cross­border populations, Internally Displaced Persons, refugees and other vulnerable groups.
• Enhance regional cooperation and cross border coordination to ensure prompt detection of WPV1 and cVDPV, and vaccination of high-risk population groups.
• Maintain these measures with documentation of full application of high quality surveillance and vaccination activities.
• At the end of 12 months without evidence of reintroduction of WPV1 or new emergence and circulation of cVDPV, provide a report to the Director-General on measures taken to implement the Temporary Recommendations.

  Additional considerations

  The Committee was encouraged by the decreasing number of WPV-1 and cVDPV2 cases, but strongly recommended that efforts in support of the polio eradication must continue, noting the ongoing impact of COVID-19 on the programme. The current favourable epidemiological trends can be attributed to the natural immunity following the explosive WPV1 and cVDPV2 transmission in 2020, the ongoing poliovirus low transmission season and the general decreasing trends of infectious diseases due to the COVID-19 lock downs with reduced population movement. The polio programme has witnessed similar favorable trends in the past that have been reversed once circumstances change. The Committee urged that the current situation must not lead to any complacency and should be considered as an opportunity to fast-track progress towards the global polio eradication by implementing high quality vaccination activities. The Committee welcomed the reports from Pakistan and Afghanistan about the successful implementation of integrated services, but remained concerned about the low IPV coverage in children with cVDPV infection and encouraged an ongoing focus on routine immunization and SIAs. The Committee also encouraged renewed cross-border efforts which countries reported to be a critical component of the polio response.

  The Committee noted with appreciation the initiation of the use of nOPV2 following the issuance of WHO's Emergency Use Listing recommendation in November 2020. Nigeria and Liberia are the countries that have implemented nOPV2 vaccination campaigns so far in 2021, targeting almost 10 million children aged less than five years. Additional 23 countries are in process of preparation to meet the global criteria for the nOPV2 use. The Committee urged the need to accelerate the preparedness for nOPV2 use under the EUL and recommended that GPEI provides all possible support to the countries in this regard. The Committee emphasized the importance of fast-tracking the review process of the nOPV2 'initial use period' to enable wider use (Phase C) after follow-up review by the SAGE. The Committee requested that sufficient nOPV2 supplies be secured noting that more countries are soon expected to meet the preparedness criteria under the initial use programme, and other countries will commence wider use during the second half of 2021.

  The Committee expressed deep concern about the ongoing challenges that the infected and vulnerable countries face towards reaching the high-risk populations. The Committee was particularly concerned about the mobile populations including the undocumented migrants as well as persisting zero-dose communities due to programmatic issues and insecurity. The Committee strongly recommended to utilize innovative strategies like rapid establishment of transit vaccination points, use of GIS to improve micro-planning (where possible) and locally appropriate operational and communication strategies to reach the zero-dose children with vaccines. The Committee welcomed the reports on planning of multi-antigen vaccination campaigns in some countries and encouraged availing all opportunities to plan and implement such campaigns and other tailored PHC strategies (e.g. delivering vitamins, deworming medication, soap etc.) to reach additional children with polio vaccine as well as to address communities' concerns and hesitancy.

  The Committee noted the ongoing political volatility in Afghanistan hampering access for vaccination campaigns, that is expected to persist over the coming months. The Committee recommended that contingency plans be established to be implemented in the event of further deterioration of the security situation with possible mass population displacement.

  The Committee noted with concern some anecdotal reports about the possibility of falsified vaccination cards used by the travelers through air and land routes. The Committee recommended to the countries to carefully investigate any such reports and put in place stringent mitigating measures.

  The Committee welcomed the progress being made in individual countries that were facing significant challenges with both polio and COVID-19. COVID-19 is also likely to continue to have a significant adverse impact on stopping polio transmission throughout 2021, with diversion of resources, barriers to successful polio campaign implementation and the consequential growing immunity gap. However, the Committee urged countries to look for where synergies can be built between polio and COVID -19 control, such as countering vaccine hesitancy, expanding and sharing testing resources, and vaccine management. Countries also need to make sure that local lockdowns and border restrictions were implemented in such a way as to avoid hampering specimen shipment and testing.

  The Committee was concerned about the growing funding gap for the polio programme and its possible implications on critical programme activities, especially in the infected low-income and conflict affected countries. The Committee called upon all the international donors and partners to maintain funding for polio eradication activities, as the potential for reversal of progress appears high, with many years of work undone rapidly if WPV1 spreads outside the endemic countries. The Committee also recommended to the programme to ensure best possible prioritization and utilization of resources in the current fiscal constrained environment.

  Based on the current situation regarding WPV1 and cVDPV, and the reports provided by affected countries, the Director-General accepted the Committee's assessment on 21 May 2021 and determined that the situation relating to poliovirus continues to constitute a PHEIC, with respect to WPV1 and cVDPV. The Director-General endorsed the Committee's recommendations for countries meeting the definition for 'States infected with WPV1, cVDPV1 or cVDPV3 with potential risk for international spread', 'States infected with cVDPV2 with potential risk for international spread' and for 'States no longer infected by WPV1 or cVDPV, but which remain vulnerable to re-infection by WPV or cVDPV' and extended the Temporary Recommendations under the IHR to reduce the risk of the international spread of poliovirus, effective 21 May 2021.