Statement of the Twentieth IHR Emergency Committee - World Health Organization

Posted: 01 Mar 2019 12:00 AM PST

The twentieth meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) regarding the international spread of poliovirus was convened by the Director General on 19 February 2019 at WHO headquarters with members, advisers and invited Member States attending via teleconference, supported by the WHO secretariat.

The Emergency Committee reviewed the data on wild poliovirus (WPV1) and circulating vaccine derived polioviruses (cVDPV). The Secretariat presented a report of progress for affected IHR States Parties subject to Temporary Recommendations. The following IHR States Parties provided an update on the current situation and the implementation of the WHO Temporary Recommendations since the Committee last met on 27 November 2018: Afghanistan, Indonesia, Mozambique, Niger, Nigeria, Pakistan and Papua New Guinea (PNG).

The committee commended all countries that presented on the quality of information provided, and the attention by the health authorities to ensuring timely and adequate responses in the field.

Wild poliovirus

Worldwide there are three remaining endemic countries, with Afghanistan and Pakistan being the only two countries where wild poliovirus transmission is continuing to be reported. The Committee noted the continued high degree of cooperation and coordination between Afghanistan and Pakistan, particularly in reaching high risk mobile populations that frequently cross the international border. The committee noted that it is more than four years since there has been international spread outside of these two epidemiologically linked countries.

However, the Committee was very concerned by the increase in WPV1 cases globally in 2018, with more cases in the two countries than in 2017. This trend appears to be continuing in 2019, with six cases already compared to two for the same period in 2018. Furthermore, international spread between the two countries has continued, after an earlier 10-month period of no international spread between the two neighbors. The committee welcomed that expansion of the target age group for vaccination at the international land border was being implemented on a trial basis in Afghanistan.

In Pakistan transmission continues to be widespread, as indicated by the number of positive environmental isolates in many areas of the country. The recent case in Lahore also indicated vulnerabilities still exist outside the high-risk corridors.

In Afghanistan, the worsened security and accessibility since early 2018 continues, and there are persistent pockets of refusals and missed children. Environmental surveillance is also finding an increased proportion of positive samples. The security situation and access would need to significantly improve for eradication efforts to progress. The recent visit of the Director General of WHO to both countries, meeting with their Heads of State, was a very positive step.

It is now more than two years since the last WPV1 was detected in Nigeria, and four years since there has been any international spread of WPV1 from the country. The Committee commended the strong efforts to reach inaccessible and trapped children in Borno, Nigeria, even in the face of increased insecurity, and noted that the inaccessible target population was now down to around 70,000 children, scattered across Borno State in smaller pockets.

Vaccine derived poliovirus

There are now eight countries in four WHO Regions responding to outbreaks of cVDPV, an unprecedented number of outbreaks in recent years. The new outbreak of cVDPV1 in Indonesia exemplifies the gaps in population immunity in many parts of the world considered polio free. It appears likely that there has been missed transmission of this virus for several years although there is no evidence so far that this has occurred outside of Papua province. However, surveillance within Indonesia urgently needs to improve, not just in Papua and West Papua provinces. PNG continues to mount a very effective response, and the committee noted that both Indonesia and PNG had been pro-active in ensuring effective coordination on both sides of the border.

The new outbreak of cVDPV2 in Mozambique is a serious concern, as it may be linked to inadequate controls placed upon unused vials mOPV2 during the earlier event there in 2017. The committee noted that the case occurred close to the border with Malawi, prompting concern about the opportunity for international spread.

The cVDPV2 outbreaks in Nigeria highlight the vulnerability to poliovirus infection in many parts of the country, with the virus spreading to areas not previously considered at high risk of polio, such as Kwara. Although no international spread of WPV1 has been observed from Nigeria since 2014, the recent cases of importation of cVDPV2 into Niger is concerning, given that cVDPVs have rarely spread across borders in the past. The committee was concerned by the lack of progress in controlling this outbreak, and the proximity of a recent case to the Republic of Benin. The committee noted the delays between case investigation and final laboratory results and suggested an analysis be undertaken to understand the reasons for this.

Repeated importations from Nigeria into Niger indicates that while strong efforts had been made to respond to risks posed by high risk populations such as cattle herders and other nomads, IDP's and refugees, more needs to be done to prevent future international spread between Nigeria and Niger. Surveillance gaps in nearby vulnerable countries in the Lake Chad area raises concerns about missed transmission in these countries.

The outbreak of cVDPV2 in Somalia and Kenya is another infrequent example of international spread of cVDPV across borders. The absence of transmission in recent months in Somalia and Kenya was welcomed, however, large inaccessible areas of Somalia are a significant constraint on achieving interruption of transmission, exacerbated by large population movements escaping conflict or driven by economic and security factors. Countries neighboring Somalia, such as South Sudan, Ethiopia and Djibouti, have areas of weak surveillance which poses a risk that international spread may go undetected.

Although there are indications that transmission may be slowing in DR Congo, the protracted duration of the outbreak, ongoing conflict, insecurity and population movements within and outside the country represent a significant risk of spread.

The committee noted that in all infected countries, routine immunization was weak, and coverage remains very poor in many areas of these countries.

Inaccessibility is a major risk to interruption of transmission in Nigeria, Niger, Somalia and Afghanistan.

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 considered the following factors in reaching this conclusion:

Rising number of WPV1 cases: Although the declaration of the PHEIC and issuance of Temporary Recommendations has reduced the risk of international spread of WPV, progress is fragile, and should international spread now occur, the impact on WPV eradication would be even more grave in terms of delaying certification and prolonging requirements for dedicated human and financial resources in support of the eradication effort. The increasing cases in Afghanistan and Pakistan with associated cross border spread of WPV1 continuing between the two countries as well as the widespread geographic detection through environmental sampling of the virus in Pakistan heighten concerns, especially as cases have increased during the current low season
Complacency: There is a risk of global complacency as the numbers of WPV cases remains low and eradication becomes a tangible reality, and a concern that removal of the PHEIC now could contribute to greater complacency.
Rising number of cVDPV outbreaks: Many countries remain vulnerable to WPV importation. Gaps in population immunity in several key high-risk areas is evidenced by the current number of cVDPV outbreaks of all serotypes, which only emerge and circulate when polio population immunity is low as a result of deficient routine immunization programs. Currently four WHO Regions are managing polio outbreaks.
International spread of cVDPV: The international spread of cVDPV2 affecting Somalia and Kenya, and Nigeria and Niger, are other examples of the current heightened risk of international spread of polioviruses. Waning population immunity to type 2 polioviruses in the face of the limited IPV supply and weak routine immunization in many countries means that significant numbers of countries neighboring these outbreaks may be at high risk of importation of cVDPV2.
Weak routine immunization: Many countries have weak immunization systems that can be further impacted by various humanitarian emergencies, 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 Somalia and Indonesia are examples of inadequate polio surveillance, heightening concerns that transmission could be missed in various countries. Similar gaps exist in Lake Chad countries and around the Horn of Africa.
Protracted outbreaks: The difficulty in rapidly controlling VDPV outbreaks in Nigeria and DR Congo was another risk.
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 and Somalia, 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)

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 26 January 2019)

Pakistan (most recent detection 28 January 2019)

Nigeria (most recent detection 27 Sept 2016)

cVDPV1

Papua New Guinea (most recent detection 7 November 2018)

Indonesia (most recent detection 25 January 2019)

cVDPV3

Somalia (most recent detection 7 Sept 2018)

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 cVDPV2s, with potential risk of international spread

*For the Lake Chad countries, this will be linked to when Nigeria is considered no longer infected by WPV1 or cVDPV2.

The world is at a critical point in polio eradication. Failure to boost population immunity through strengthening routine immunization, and failure to prevent outbreaks through implementation of high quality SIAs in areas of known high risk, could jeopardize or severely delay polio eradication. The current situation calls for unabated efforts and use of every tool available, to achieve the goal in these most challenging countries. Particularly in the three remaining endemic countries, further engagement with senior levels of government and other key stakeholders is needed to advocate for polio eradication, and ensure all levels of government maintain a strong commitment until the job is done.

Noting the spread of polioviruses in several areas close to international borders, the committee strongly urges that surveillance, population immunity assessments and outbreak preparedness activities intensify in all neighboring countries, particularly in Benin, Malawi, Ethiopia, South Sudan, Djibouti, Lake Chad basin countries and the Central African Republic. There needs to be a renewed urgency to addressing these gaps wherever they exist.

Countries using mOPV2 should take great care in accounting for all vials of the vaccine, to avoid unauthorized and inappropriate use outside a globally agreed SIA campaign.

Based on the current situation regarding WPV1 and cVDPV, and the reports provided by Afghanistan, Indonesia, Mozambique, Nigeria, Niger, Pakistan and Papua New Guinea, the Director-General accepted the Committee's assessment and on 28 February 2019 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 28 February 2019.

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