Author: Rosaline Horlar

The Twenty-fourth meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) on the international spread of poliovirus was convened by the Director General on 26 March 2020 with committee members only attending
via teleconference, supported by the WHO Secretariat.  In order to ease the burden on affected State Parties in the exceptional situation following the determination of the COVID-19 outbreak as a Public Health Emergency of International Concern
(PHEIC) on 30 January 2020, characterized as a pandemic on 11 March 2020, the invited State Parties were asked to present their reports electronically only instead of attending via teleconference.  Reports were received from Afghanistan, Burkina
Faso, Central African Republic, Cote d’Ivoire, Democratic Republic of Congo (DR Congo), Ethiopia, Ghana, Pakistan, and Philippines.

The Emergency Committee reviewed the data on wild poliovirus (WPV1) and circulating vaccine derived polioviruses (cVDPV).  The WHO Secretariat presented a report of progress for affected IHR States Parties subject to Temporary Recommendations.

Wild poliovirus

The Committee remains gravely concerned by the significant increase in WPV1 cases globally in 2019 and 2020, with 175 cases in 2019 compared to 33 in 2018, and already 32 cases as at 17 March 2020, compared to six for the same period in 2019, with no
significant success yet in reversing this trend.

In Pakistan transmission continues to be widespread, as indicated by both acute flaccid paralysis (AFP) surveillance and environmental sampling. While the issues of vaccine hesitancy and refusals by individuals and communities and problems with management
of the national polio program are being addressed, these are yet to have impact on the current worrying epidemiology.  The added pressure on the program due to detection of cVDPV2 and ongoing spread in several provinces (see below) has continued
into 2020.

In Afghanistan, the security situation remains very challenging.  Inaccessibility and missed children particularly in the Southern Region have led to a large cohort of susceptible children in this part of Afghanistan.  The risk of a major upsurge
of cases is growing, with other parts of the country that have been free of WPV1 for some time now at risk of outbreaks. This would again increase the risk of international spread. 

The  Committee noted that based on sequencing of viruses, there were recent instances of international spread of viruses from Pakistan to Afghanistan and also from Afghanistan to Pakistan.  The recent increased frequency of WPV1 international
spread between the two countries suggests that rising transmission in Pakistan and Afghanistan correlates with increasing risk of WPV1 exportation beyond the single epidemiological block formed by the two countries. 

The Committee noted the continued cooperation and coordination between Afghanistan and Pakistan, particularly in reaching high risk mobile populations that frequently cross the international border and welcomed the all-age vaccination now being taken
at key border points between the two countries. 

Vaccine derived poliovirus (VDPV)

The multiple cirulating VDPV (cVDPV) outbreaks in four WHO regions (African, Eastern Mediterranean, South-east Asian and Western Pacific Regions) are very concerning, with two new countries reporting outbreaks since the last meeting (Malaysia and Burkina
Faso).  Unlike historical experience, cross border spread of cVDPV2 has become quite common, with recent spread from Angola to DR Congo and Zambia, and from Chad and CAR to Cameroon, and from Ghana to Burkina Faso.  In addition, local emergences
attributable to mOPV2 use have recently occurred in Togo, Chad and Ethiopia.

The Committee noted that the GPEI has published a strategy to address cVDPV2 outbreaks but was extremely concerned that the monovalent OPV2 stockpile was still depleted.  The Committee strongly supports the development and proposed Emergency Use
Listing of the novel OPV2 vaccine which should become available mid-2020, and which it is hoped will result in no or very little seeding of further outbreaks. 

Impact of COVID-19

The Committee noted the very recent policy guidance of the GPEI:

• GPEI recommendations for countries during the COVID-19 pandemic. This document summarizes the recommendations from the Polio Oversight Board meeting on 24 March 2020 which calls for postponement of both preventive and outbreak response campaigns,
  while ensuring surveillance and nOPV2 development and roll out plans continue in full.
• The COVID-19 Polio programme continuity plan. The operational guide was developed in collaboration with the regional polio eradication teams and the GPEI Partners to ensure essential GPEI functions continue, polio programme personnel and staff are
  kept safe, and to plan for a fast and effective resumption of polio eradication activities including supplementary immunization activities as soon as the public health situation with COVID-19 allows. 

The Committee is extremely concerned about the impact of the COVID-19 pandemic on the risk of heightened transmission of polio and consequently the potential for international spread and significant reversal of polio eradication.     

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.  However
noting that some if not many international borders are closed to prevent  international spread of COVID-19, State Parties may not currently be able to enforce the Temporary Recommendations in all places. The Committee strongly urges countries
subject to these recommendations to maintain a high state of readiness to implement them as soon as possible ensuring the continued safety of travelers as well as health professionals .  The Committee recognizes the concerns regarding the lengthy
duration of the polio PHEIC, but concludes that the current situation is extraordinary, with clear ongoing risk of international spread and ongoing need for coordinated international response. The Committee considered the following factors in reaching
this conclusion:

• Rising risk of WPV1 international spread: The progress made in recent years appears to have reversed, with the Committee’s assessment that the risk of international spread is at the highest point
  since 2014 when the PHEIC was declared. This risk assessment is based on the following:
  • the WPV1 exportation in 2019 from Pakistan to Iran and to Afghanistan, and more recently spread from Afghanistan to Pakistan;
  • ongoing rise in the number of WPV1 cases and positive environmental samples in Pakistan, and to a lesser extent Afghanistan;
  • the quickly increasing cohort of unvaccinated children in Afghanistan, with the risk of a major outbreak imminent if nothing is done to access these children;
  • the urgent need to overhaul the leadership and strategy of the program in Pakistan, which although already commenced, is likely take some time to lead to more effective control of transmission
    and ultimately eradication;
  • increasing community and individual resistance to the polio program.
• Rising risk of cVDPV international spread: The clearly documented increased spread in recent months of cVDPV2 demonstrate the unusual nature of the current situation, as international spread of cVDPV
  in the past has been very infrequent.  The number of new emergences of cVDPV2 in Africa raises further concern.  The risk of new outbreaks in new countries is considered extremely high, even probable. 
• COVID-19:  This new and unprecedented pandemic is likely to substantially negatively impact the polio eradication program and outbreak control efforts.  There is a risk of exportation of both
  WPV1 and cVDPV to known high risk countries, to which it may take a lot of time and effort to adequately respond.
• Falling PV2 immunity:  Global population mucosal immunity to type 2 polioviruses (PV2) continues to fall, as the cohort of children born after OPV2 withdrawal grows, exacerbated by poor coverage
  with IPV particularly in some of the cVDPV infected countries.
• Multiple outbreaks: The evolving and unusual epidemiology resulting in rapid emergence and evolution of cVDPV2 strains is extraordinary and not yet fully understood and represents an additional risk
  that is yet to be quantified.
• Weak routine immunization: Many countries have weak immunization systems that can be further impacted by various humanitarian emergencies including COVID19, and 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.
• Surveillance gaps: The appearance of highly diverged VDPVs in the Philippines, Somalia and Indonesia are examples of inadequate polio surveillance, heightening concerns that transmission could be missed
  in various countries.  Furthermore, the missed transmission in China for a year illustrates that even countries with generally good surveillance can miss VDPV transmission.  COVID-19 is likely to have a negative impact on polio surveillance
  also.
• Lack of access: Inaccessibility continues to be a major risk, particularly in several countries currently infected with WPV or cVDPV, i.e. Afghanistan, Nigeria, Niger, Somalia and Myanmar, which all
  have sizable populations that have been unreached with polio vaccine for prolonged periods.
• Population movement: The risk is amplified by population movement, whether for family, social, economic or cultural reasons, or in the context of populations displaced by insecurity and returning refugees.
  There is a need for international coordination to address these risks.  A regional approach and strong cross­border cooperation is required to respond to these risks, as much international spread of polio occurs over land borders.

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:

• States infected with WPV1, cVDPV1 or cVDPV3, with potential risk of international spread.
• States infected with cVDPV2, with potential risk of international spread.
• 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 (e.g. Borno State, Nigeria)

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                                                                                             

Afghanistan                               (most recent detection 25 February 2020)  

Pakistan                                                (most recent detection 2 March 2020)

Nigeria                                      (most recent detection 27 Sept 2016)           

cVDPV1

Malaysia                                     (most recent detection 26 October 2019)

Myanmar                                   (most recent detection 9 August 2019)

Philippines                                 (most recent detection 28 October 2019)

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.

Afghanistan           (most recent detection 8 January 2020)

Angola                      (most recent detection 9 February 2020)

Benin                        (most recent detection 9 December 2020)

Burkina Faso          (most recent detection 11 January 2020)

Cameroon              (most recent detection 30 January 2020)

CAR                           (most recent detection 5 February 2020)

Chad                         (most recent detection 5 February 2020)

Cote d’Ivoire          (most recent detection 11 February 2020)

China                        (most recent detection 25 April 2019)

DR Congo                 (most recent detection 22 January 2020)

Ethiopia                (most recent detection 21 February 2020)

Ghana                      (most recent detection 28 January 2020)

Malaysia                  (most recent detection 18 January 2020)

Niger                         (most recent detection 3 April 2019)

Nigeria                  (most recent detection1 January 2020)

Pakistan                   (most recent detection 12 February 2020)

Philippines              (most recent detection 16 January 2020)

Somalia                    (most recent detection 4 February 2020)

Togo                          (most recent detection 10 January 2020)

Zambia                     (most recent detection 25 November 2019)

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.
• 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.
• Encourage residents and long­term visitors to receive a dose of IPV four weeks to 12 months prior to international travel; those undertaking urgent travel (i.e. within four weeks) should be encouraged to receive a dose at least by the time of departure.
• 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.
• 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 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

  • Kenya cVDPV2 (last env positive specimen 21 March 2018)
  • Mozambique cVDPV2 (last virus detected 17 December 2018)
  • PNG cVDPV1 (last environmental positive specimen 6 November 2018)
  • Indonesia cVDPV1 (last virus detected 13 February 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

Impact of COVID-19 on the polio program:

• The committee urges all countries, but particularly those at high risk of polio, to maintain a high level of polio surveillance throughout the pandemic period, noting that the postponement of polio immunization campaigns whether preventive or in response to outbreaks may lead to an increase in polio transmission including international spread.  Maintainenance of access to laboratory diagnosis in the face of widespread transport and shipping disruption is critical.
• Secondly, countries affected by campaign postponement should strive to maintain a high degree of operational readiness in order that immunization activities, including border vaccination, can resume quickly adhering to principles of good hygiene and safety for the vaccinee as well as for the health professionals to prevent  COVID-19 spread.  This includes ensuring teams have access to appropriate personal protective equipment.
• Given the risk of international spread, countries need to ensure that they are ready to use appropriate vaccines, as recommended by the Strategic Advisory Group of Experts on Immunization,  in response to new outbreaks.
• The committee urged countries to maximize the use of polio assets to synergistically address the COVID19 pandemic, noting that polio affected countries may be vulnerable to poorer outcomes in the pandemic due to health care system fragility and poorer health status of the population generally. 
• Lastly the pandemic should serve as a reminder to high risk countries with poor immunization coverage that infectious disease outbreaks can lead to social and economic disruption as well as straining the health care system, and countries can increase their population resilience and recovery through prioiritising  robust immunization programmes. This is relevant not only to polio, but to all other vaccine preventable diseases particularly measles.

Based on the current situation regarding WPV1 and cVDPV, and the reports provided by affected countries, the Director-General accepted the Committee’s assessment and on 7 April 2020 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 7 April 2020. 

 

 

 

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