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Statement of the 13th IHR Emergency Committee regarding the international spread of poliovirus

WHO statement
2 May 2017

The thirteenth 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 24 April 2017.

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 7 February 2017: Afghanistan, Pakistan, Nigeria, and Equatorial Guinea. The committee also invited the Russian Federation and the Netherlands to provide information about polio events in their respective territories.

Wild polio

Overall the Committee was encouraged by continued steady progress in all three WPV1 infected countries, Pakistan, Afghanistan, and Nigeria, and the fall in the number of cases globally. While falling transmission in these three countries decreased the risk of international spread, the consequences should spread occur would represent a significant set-back to eradication and a risk to public health.

The Committee commended the efforts of Pakistan to further strengthen surveillance, and noted that the intensity of environmental surveillance in the country is now at unprecedented levels in the history of the polio eradication program. However, the recent orphan virus detected in Punjab province highlighted there are still gaps in surveillance. The Committee applauded the information that there were no fully inaccessible children in 2017, and the steady progress in the quality of supplementary immunization activities (SIA).

The Committee welcomed the reduction in Afghanistan in the number of inaccessible children and particularly the progress in reaching high-risk populations in Kunduz. However, the recent international spread of WPV1 from Pakistan into Kandahar, Hilmand and Kunduz provinces of Afghanistan illustrated that population movement between these two countries is an ongoing challenge to achieving eradication, and that gaps in population immunity continued despite improving SIA quality.

The Committee was pleased with the continued emphasis on cooperation along the long international border between the two countries noting that this sub region constitutes a single epidemiological block, due to population movement, shared nomadic groups, and border populations that straddle the border. The principle challenge remains the shared common poliovirus reservoirs between both countries.

The Committee noted that there were no new WPV1 cases detected in Nigeria since August 2016. However, as there remains a substantial population in Northern Nigeria that is totally or partially inaccessible, the committee concluded that there is a high risk that polioviruses are still circulating in this sub-region. Reaching these populations is critically important for the polio eradication effort, but it is acknowledged that there are significant security risks that may pose a danger to polio eradication workers and volunteers. The Committee noted that working under this threat is likely to negatively impact on the quality of the interventions. Nigeria has already adopted innovative and multi-pronged approaches to this problem, and these innovations should be continued. Nigeria also reported on ongoing efforts to ensure vaccination at international borders (including at airports), other transit points, IDP camps and in other areas where nomadic populations existed.

There was ongoing concern about the Lake Chad basin region, and for all the countries that are affected by the insurgency, with the consequent lack of services and presence of IDPs and refugees. The risk of international spread from Nigeria to the Lake Chad basin countries or further afield in sub-Saharan Africa remains high. The committee was encouraged that the Lake Chad basin countries including Nigeria, Cameroon, Chad, Niger and the Central African Republic (CAR), continued to be committed to sub-regional coordination of immunization and surveillance activities.

While Equatorial Guinea remains vulnerable, the committee was pleased that there had been some recent improvement in AFP surveillance and a plan to introduce environmental surveillance. The plan to address gaps in population immunity through SIA’s and improvements to routine immunization are welcomed and should be monitored to ensure success.

The Netherlands reported an incident in which a breach of containment at a vaccine manufacturing plant led to the infection of a worker with WPV2 at a vaccine manufacturing plant. This event is serious and subject to ongoing monitoring, but the committee noted that some important lessons can be learnt in the response to this event. While the risk of international spread is very low, the public health consequences of any further transmission of this eradicated virus would be extremely serious.

Vaccine derived poliovirus

The committee noted that there were no new outbreaks of cVDPV, and no new cases in the three current cVDPV2 outbreaks (Borno and Sokoto in northern Nigeria, and in Quetta Pakistan). However, these outbreaks highlighted the presence of vulnerable under immunized populations in countries with endemic transmission. The committee noted the comprehensive response to these outbreaks.

The Russian Federation provided an update on the actions taken following the detection of VDPV2s in two children from the Chechen Republic and Moscow, but the committee noted there were still some important gaps in the information and the final classification of the case is therefore pending. However, the surveillance and immunization activities taken in response to this event were welcomed, and there appears to be very little risk of international spread.

In Lao PDR, the most recent case of cVDPV had onset in January 2016, and based on the most recent outbreak response assessment and the criteria of the committee, the country is no longer considered as infected, but remains vulnerable.

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 revised Temporary Recommendations for a further three months. The Committee considered the following factors in reaching this conclusion:

  • The continuing international spread of WPV1 between Pakistan and Afghanistan in the last 3 months.
  • The potential risk of further spread through population movement, whether for family, social and cultural reasons, or in the context of populations displaced by insecurity, returning refugees, or nomadic populations, and the need for international coordination to address these risks, particularly between Afghanistan and Pakistan, and Nigeria and its Lake Chad neighbors.
  • The current special and extraordinary context of being closer to polio eradication than ever before in history, with the incidence of WPV1 cases in 2017 the lowest ever recorded.
  • 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 an increasing probability.
  • The outbreak of WPV1 (and cVDPV) 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 high.
  • 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 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 Pakistan, 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 the post Ebola context;
    • The global shortage of IPV which poses an additional threat.

Notwithstanding the concept that Afghanistan and Pakistan form a single epidemiological block with shared poliovirus reservoirs straddling the international border, in the context of the IHR, transmission across the border constitutes international spread between State Parties. Many other State Parties equally share cross border populations with neighboring countries, and form epidemiological blocks with respect to disease transmission. The existence of such epidemiological blocks does not negate the actual or potential public health risk to other States through international spread, requiring a coordinated international response, pre-conditions for determining a PHEIC under the IHR.

Review of Temporary Recommendations

As global eradication is now closer than ever before, the committee concluded that it was timely to revise and update the Temporary Recommendations to re-calibrate according to current risks. At the time of the PHEIC declaration in 2014, ten countries were WPV infected, seven of them following exportation of virus resulting in re-infection (ie Syria, Iraq, and Israel in the Middle East, and Somalia, Ethiopia, Cameroon, and Equatorial Guinea in Africa) and the Temporary Recommendations particularly focused on exporting countries. However, as nearly three years have passed since the last re-infected country, Somalia, recorded its last WPV case, the global context has changed significantly, and all three endemic countries where transmission is now occurring represent a serious risk to polio eradication, irrespective of whether exportation events have been detected or not. The committee noted gaps in surveillance in many high risk areas, so that exportation events might not be detected in a timely manner. The committee also has received evidence based on modelling that the imposition of the Temporary Recommendations was cost effective, providing further justification for the extension of the relevant Temporary Recommendations to all WPV infected countries.

Based on these considerations, the committee changed the categories of countries subject to Temporary Recommendations, with the aim of strengthening them for WPV, and recognizing the changed context with respect to cVDPV2.

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; and
  • 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 samples collected within 12 months of the last case have also tested negative, whichever is the longer.
  • Environmental isolation of WPV1 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.
  • These criteria may be varied for the endemic countries, where more rigorous assessment is needed in reference to surveillance gaps (eg Borno).

TEMPORARY RECOMMENDATIONS

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

(Currently Pakistan, Afghanistan and Nigeria)

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.
  • 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).
  • These countries should 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.
  • 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 cVDPV2s

(Currently Nigeria and Pakistan)

These countries should:

  • 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.
  • 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 IPV (if available in country) 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.
  • 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

  • Cameroon (last case 9 Jul 2014)
  • Niger (last case 15 Nov 2012)
  • Chad (last case 14 Jun 2012)
  • Central African Republic (last case 8 Dec 2011)

cVDPV

  • Ukraine (last case 7th July 2015)
  • Madagascar (last case 22nd August 2015)
  • Myanmar (last case 5th October 2015)
  • Guinea (last case 14th December 2015)
  • Lao PDR (last case 11th January 2016)

These countries should:

  • Urgently strengthen routine immunization to boost population immunity.
  • Enhance surveillance quality 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.

*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. Based on the last cases (above) in Ukraine the report will be due August 2017, for Myanmar in November 2017, for Madagascar in September 2017, for Guinea in January 2017, and in Lao PDR February 2018).

Additional considerations

The committee advised WHO to carefully review the event in the Netherlands, and also to review all applicable existing guidance to prevent and respond to such accidental release, and develop further guidance as necessary.

The committee noted that the VDPV in the Russian Federation was still unclassified, and that the event would be given further consideration at the European Regional Certification Commission in June and is still under review by the Advisory Committee for the release of mOPV2 vaccine.

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 all countries that were previously subject to Temporary Recommendations (Somalia, Ethiopia, Syria, Iraq and Israel).

The Committee noted a detailed analysis of the public health benefits and costs of implementing temporary recommendations was completed and was currently undergoing peer review prior to publication.

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, and careful assessment of where insecurity and inaccessibility impact on surveillance. Similarly, there needs to be tracking of populations where there are high proportions of unvaccinated children due to inaccessibility.

Based on the advice concerning WPV1 and cVDPV, and the reports made by Afghanistan, Pakistan, Nigeria, and Equatorial Guinea, the Director General accepted the Committee’s assessment and on 2 May 2017 determined that the events relating to poliovirus continue to constitute a PHEIC, with respect to WPV1 and cVDPV. The Director General endorsed the Committee’s recommendations for countries falling into the definition for ‘States infected with WPV1, cVDPV1 or cVDPV3 with potential risk for international spread’, ‘States infected with cVDPV2’ 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 as revised by the Committee under the IHR to reduce the risk of international spread of poliovirus, effective 2 May 2017.

The Director General thanked the Committee Members and Advisors for their advice.