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Statement of the 11th IHR Emergency Committee regarding the international spread of poliovirus

WHO statement
11 November 2016

The eleventh meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) regarding the international spread of poliovirus was convened via teleconference by the Director General on 11 November 2016.

The Emergency Committee reviewed the data on wild poliovirus (WPV1) and circulating vaccine­derived polioviruses (cVDPV). The Secretariat presented a report of progress for affected IHR States Parties subject to Temporary Recommendations. The following IHR States Parties presented an update on the implementation of the WHO Temporary Recommendations since the Committee last met on 11 August 2016: Afghanistan, Pakistan, Nigeria, Cameroon, Chad and Niger.

Wild polio

Overall the Committee was encouraged by steady progress in Pakistan and Afghanistan, but noted that the detection of four cases of wild poliovirus type 1 (WPV1) in Nigeria was a setback to polio eradication. The committee was reassured and impressed by the rapid response of the polio eradication programme in Nigeria. The committee conceded that such setbacks can be anticipated as eradication gets closer, but also recognised that these are a threat to achieving the global polio endgame.

The Committee welcomed the progress being made in Afghanistan and Pakistan, and the renewed emphasis on cooperation along the long international border between the two countries noting that this sub region constitutes an epidemiological block.

In Pakistan, the Committee recognized the large decrease in inaccessible children in 2016 was a significant achievement. However, the recent exportation of WPV1 from Pakistan into Paktika province of Afghanistan illustrated the difficulty of halting international spread between these two countries. Furthermore, the proportion of environmental samples testing positive for WPV1 in Pakistan has remained around 10% throughout 2016, with positive samples being detected across a wide geographic area. In most cases, environmental samples have tested positive in areas where no wild polio cases have been detected suggesting high population immunity but also raising the possibility of missed cases.

The Committee was concerned by the deteriorating security in parts of Afghanistan leading to more children becoming inaccessible, heightening anxiety about completion of eradication. The recent outbreak in Bermel district in Paktika province illustrates the vulnerability of Afghanistan in terms of pockets of high risk populations, with low population immunity and high degree of mobility, including refugees, returnees, IDP’s and nomadic groups. The committee noted that the last exportation from Afghanistan (to Pakistan, 14 Sept 2015) was more than 13 months ago.

The Committee commended Nigeria for its rapid response to the new WPV1 cases, including release of emergency funding, and also for the transparency of its communication. However, there remain substantial populations in Northern Nigeria that are totally or partially inaccessible, and where there are significant security risks that may pose danger to polio eradication workers and volunteers. Noting that the four recently isolated polioviruses had been circulating for three to four years, the committee concluded that it is highly likely that polioviruses are circulating in these areas so that reaching these populations is critically important for the polio eradication effort. The risk of international spread to Lake Chad basin countries or further afield in sub-Saharan Africa is considered very high. The committee was encouraged that the Lake Chad basin countries including Nigeria, Cameroon, Chad, Niger and the Central African Republic, had established a Task Force for sub-regional coordination. This opens up opportunities to access inaccessible areas e.g. Nigerian islands in Lake Chad, inaccessible from Nigeria, could possibly be accessed from Chad.

The Committee received final reports from Somalia, Cameroon and Equatorial Guinea, as these three countries had been on the list of members vulnerable to importation of poliovirus, a risk category defined by the IHR Polio Emergency Committee. After 12 months on this list, countries are asked to provide a report to the committee outlining the activities they have undertaken to reduce vulnerability to poliovirus outbreaks. Based on these reports, the Committee advises on whether or not countries should stay on the vulnerable list. After reviewing reports from these countries the Committee made the following recommendations: Based on its geographical proximity to the WPV1 outbreak and the likelihood of circulating poliovirus in the Lake Chad region, Cameroon is still considered vulnerable. Equatorial Guinea also remains vulnerable, based on very sub-optimal polio eradication activities including poor surveillance, low routine immunisation coverage, and waning national efforts to address this vulnerability. In contrast, although Somalia has a large population that is inaccessible and not vaccinated, the surveillance in this region is sufficient to rule out transmission and in other areas of the country the national programme remains strong.

Vaccine derived poliovirus

The Committee noted that there have been no new cases of cVDPV since the previous meetings in May and August 2016 respectively. However, a healthy child contact of a WPV1 case from Borno, Nigeria tested positive in August 2016 for the same strain of cVDPV2 as found in the positive environmental sample in March 2016, indicating ongoing circulation in Borno state. It was concluded that cVDPV2 was likely present but undetected in the same inaccessible populations as WPV1, with ongoing risk of international spread to neighboring countries.

In Guinea, the most recent case of cVDPV had onset in December 2015. The Committee, however, felt there is a continued risk of spread to neighbouring areas both within Guinea and to the neighbouring post-Ebola affected countries of Liberia and Sierra Leone, as active surveillance has only recently started and the likelihood of missing transmission cannot be ruled out. Addressing surveillance gaps in Liberia and Sierra Leone still requires more efforts.

The Committee received ‘12 month reports’ from Myanmar and Madagascar, and noted that it is now more than 13 months since cases of cVDPV were detected in these countries. Although some gaps in surveillance remain, circulation appears to have ceased.

Conclusion

The Committee unanimously agreed that the international spread of poliovirus remains a Public Health Emergency of International Concern (PHEIC), and recommended the extension of the Temporary Recommendations for a further three months. The Committee considered the following factors in reaching this conclusion:

  • The new outbreak of WPV1 in Nigeria highlighting that there are high-risk areas where surveillance is compromised by inaccessibility, resulting in ongoing circulation of WPV for several years without detection. The risk of transmission in the Lake Chad sub-region appears very high.
  • The continued international spread of wild poliovirus during 2016 from Pakistan to Afghanistan, resulting in intense transmission in vulnerable populations.
  • The persistent, wide geographical distribution of positive WPV1 in environmental samples in Pakistan.
  • The current special and extraordinary context of being closer to polio eradication than ever before in history.
  • The risk and consequent costs of failure to eradicate globally one of the world’s most serious vaccine preventable diseases. Even though global transmission has fallen dramatically and with it the likelihood of international spread, the consequences and impact of international spread should it occur would be grave.
  • The possibility of global complacency developing as the numbers of polio cases continues to fall and eradication becomes a possibility.
  • The serious consequences of further international spread for the increasing number of countries in which immunization systems have been weakened or disrupted by conflict and complex emergencies. Populations in these fragile states are vulnerable to outbreaks of polio. Outbreaks in fragile states are exceedingly difficult to control and threaten the completion of global polio eradication during its end stage.
  • The continued necessity for a coordinated international response to improve immunization and surveillance for wild poliovirus, to stop international spread and reduce the risk of new spread.
  • The importance of a regional approach and strong cross­border cooperation, as much international spread of polio occurs over land borders, while also recognizing that the risk of distant international spread remains from zones with active poliovirus transmission.
  • Additionally with respect to cVDPV:
    • cVDPVs also pose a risk for international spread, which without an urgent response with appropriate measures threatens vulnerable populations as noted above;
    • The ongoing circulation of cVDPV2 in Nigeria and possibly in Guinea, and in Lao PDR, demonstrates significant gaps in population immunity at a critical time in the polio endgame;
    • The ongoing urgency to prevent type 2 cVDPVs following the globally synchronized withdrawal of the type 2 component of the oral poliovirus vaccine in April 2016;
    • The ongoing challenges of improving routine immunization in areas affected by insecurity and other emergencies, including Ebola;
    • The global shortage of IPV which poses an additional threat from cVDPVs.

Risk categories

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

Wild poliovirus
  • States currently exporting wild poliovirus;
  • States infected with wild poliovirus but not currently exporting;
  • States no longer infected by wild poliovirus, but which remain vulnerable to international spread.
Circulating vaccine derived poliovirus
  • States currently exporting cVDPV;
  • States infected with cVDPV but not currently exporting;
  • States no longer infected by cVDPV, but which remain vulnerable to the emergence and circulation of VDPV.

The Committee applied the following criteria to assess the period for detection of no new exportations and the period for detection of no new cases or environmental isolates of wild poliovirus or cVDPV:

Criteria to assess States no longer exporting (detection of no new wild poliovirus or cVDPV exportation)
  • Poliovirus Case: 12 months after the onset date of the first case caused by the most recent exportation 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 the first case caused by the most recent importation have been tested for polio and excluded for newly imported WPV1 or cVDPV, and environmental samples collected within 12 months of the first case have also tested negative, whichever is the longer.
  • Environmental isolation of exported poliovirus: 12 months after collection of the first positive environmental sample in the country that received the new exportation PLUS one month to account for the laboratory testing and reporting period.
Criteria to assess States no longer infected (detection of no new wild poliovirus 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 samples collected within 12 months of the last case have also tested negative, whichever is the longer.
  • Environmental isolation of wild poliovirus or cVDPV (no poliovirus case): 12 months after collection of the most recent positive environmental sample PLUS one month to account for the laboratory testing and reporting period.

Temporary recommendations

States currently exporting wild poliovirus or cVDPV

Currently Pakistan (last wild poliovirus exportation: 2 Aug 2016, to Afghanistan).

Exporting 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; where such declaration has already been made, this emergency status should be maintained.
  • Ensure that all residents and long­term visitors (i.e. > four weeks) of all ages, receive a dose of oral poliovirus vaccine (OPV) 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 OPV 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 travellers.
  • Ensure that such travellers 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 travellers from all points of departure, irrespective of the means of conveyance (e.g. road, air, sea).
  • Recognising that the movement of people across the border between Pakistan and Afghanistan continues to facilitate exportation of wild poliovirus, both countries should further intensify cross­border efforts by significantly improving coordination at the national, regional and local levels to substantially increase vaccination coverage of travellers crossing the border and of high risk cross­border populations. Both countries have maintained permanent vaccination teams at the main border crossings for many years. 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 travellers that are identified as unvaccinated after they have crossed the border.
  • Maintain these measures until the following criteria have been met: (i) at least six months have passed without new exportations 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 criteria of a ‘state no longer exporting’.
  • Provide to the Director General a monthly report on the implementation of the Temporary Recommendations on international travel, including the number of residents whose travel was restricted and the number of travellers who were vaccinated and provided appropriate documentation at the point of departure.
States infected with wild poliovirus or cVDPVs but not currently exporting

Infected countries (WPV1)

  • Nigeria (last case 21 August 2016)
  • Afghanistan (last case 7 October 2016)

Infected countries (cVDPV)

  • Nigeria (last isolate from a community survey 26 August 2016)
  • Guinea (last case 14 December 2015)
  • Lao People’s Democratic Republic (last case 11 January 2016)

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; where such declaration has already been made, this emergency status should be maintained.
  • Encourage residents and long­term visitors to receive a dose of OPV or 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 travellers 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 substantially increase vaccination coverage among refugees, travellers and cross­border populations.
  • Maintain these measures until the following criteria have been met: (i) at least six months have passed without the detection of wild poliovirus transmission or circulation of VDPV 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 wild poliovirus or cVDPV, but which remain vulnerable to international spread, and states that are vulnerable to the emergence and circulation of VDPV

WPV1

  • Cameroon (last case 9 July 2014)
  • Niger (last case 15 November 2012)
  • Chad (last case 14 June 2012)
  • Equatorial Guinea (last case 13 May 2014)
  • Central African Republic* (last case 8 December 2011)

cVDPV

  • Ukraine (last case 7 July 2015)
  • Madagascar (last case 22 August 2015)
  • Myanmar (last case 5 October 2015)

* Central African Republic was added on the basis that it is included in the coordinated response in the Lake Chad sub-region, and therefore logically should be subject to the same Temporary Recommendations as the other Lake Chad countries.

These countries should:

  • Urgently strengthen routine immunization to boost population immunity.
  • Enhance surveillance quality to reduce the risk of undetected wild poliovirus 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 wild poliovirus 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 wild poliovirus or new emergence and circulation of cVDPV, provide a report to the Director General on measures taken to implement the Temporary Recommendations.

**For the Lake Chad countries, this will be 12 months after the last case of WPV1 or cVDPV2, whichever is the latest, in the sub-region. For Equatorial Guinea, this will be determined at the next meeting in February 2017, when the country will be invited to present a statement to the committee. Based on the last cases (above) in Ukraine the report will be due August 2017, for Myanmar in November 2017, and for Madagascar in September 2017.

Additional considerations for all infected and high risk countries

The Committee strongly urged global partners in polio eradication to provide optimal support to all infected and vulnerable countries at this critical time in the polio eradication programme for implementation of the Temporary Recommendations under the IHR, as well as providing ongoing support to countries, such as Somalia that were recently subject to Temporary Recommendations. The Committee requested that future secretariat reports should include a cumulative table of countries which have been removed from the ‘vulnerable country’ list, with comments on the current situation in those countries.

Learning from recent events in Nigeria, the committee requested the secretariat provide a global report on all inaccessible areas where polio surveillance may be compromised. Recognizing that cVDPV illustrates serious gaps in routine immunization programmes in otherwise polio free countries, the Committee recommended that the international partners in routine immunization, for example Gavi, should assist affected countries to improve the national immunization programme.

The Committee noted the threat posed to eradication efforts caused by the global IPV shortage and requested that SAGE continue to monitor and make recommendations to address this situation.

The Committee noted the Secretariat’s report on the identification of Sabin 2 virus detected in environmental samples in India probably due to the ongoing use of tOPV in the private sector. As Sabin 2 virus has also been detected in Russia, Nigeria and Afghanistan, the Committee requested a full report on this at the next meeting.

The Committee noted a more detailed analysis of the public health benefits and costs of implementing temporary recommendations was under way and requested a report be made available to the committee in February 2017.

The Committee urged all countries to avoid complacency which could easily lead to a polio resurgence. Surveillance particularly needs careful attention to quickly detect any resurgent transmission.

Based on the advice concerning wild poliovirus and cVDPV, and the reports made by Afghanistan, Pakistan, Nigeria, Cameroon, Chad and Niger, the Director General accepted the Committee’s assessment and on 18 November 2016 determined that the events relating to poliovirus continue to constitute a PHEIC, with respect to wild poliovirus and cVDPV. The Director General endorsed the Committee’s recommendations for countries falling into the definition of ‘States currently exporting wild polioviruses or cVDPV’, for ‘States infected with wild poliovirus or cVDPV but not currently exporting’ and for ‘States no longer infected by wild poliovirus, but which remain vulnerable to international spread, and states that are vulnerable to the emergence and circulation of VDPV’ and extended the Temporary Recommendations as revised by the Committee under the IHR to reduce the international spread of poliovirus, effective 18 November 2016.

The Director General thanked the Committee Members and Advisors for their advice and requested their reassessment of this situation within the next three months.