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Twelfth meeting of the Emergency Committee under the International Health Regulations (2015) regarding the international spread of poliovirus

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The twelfth meeting of the Emergency Committee (EC) under the International Health Regulations (2005) (IHR) regarding the international spread of poliovirus was convened via teleconference by the Director General on 7 February 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 11 November 2016: Afghanistan, Pakistan, Nigeria, and Central African Republic. The committee also invited the Russian Federation to provide information about a VDPV event in its territory.

Wild polio

Overall the Committee was encouraged by steady progress in Pakistan and Afghanistan, and was reassured and impressed by the rapid response of the polio eradication programme in Nigeria.

The committee welcomed the dedication in Pakistan to further strengthen surveillance, and in particular the expansion of environmental surveillance to improve detection. The intensity of environmental surveillance is now at unprecedented levels, so that it is likely detections may increase even as transmission in cases is falling. These data need careful interpretation, and the committee acknowledged that this also includes interpretation of data concerning cross-border transmission. The Committee also applauded the information that there were no fully inaccessible children in 2017. However, the recent exportation of WPV1 from Pakistan into Kandahar province of Afghanistan illustrated the difficulty of halting international spread between these two countries.

While the Committee applauded the efforts of Afghanistan to reach inaccessible children and noted the overall reduction in these numbers, the continuing insecurity in parts of Afghanistan means that substantial numbers of children remain inaccessible, heightening anxiety about completion of eradication.

The Committee welcomed the continued emphasis on cooperation along the long international border between the two countries noting that this sub region constitutes an epidemiological block. The committee continues to believe that the international border represents a significant opportunity to vaccinate children who may otherwise have been missed, and welcomed the increase in the number of border vaccination teams. Opportunities to install teams at more informal border crossings should be encouraged.

The Committee commended Nigeria for its rapid response to the WPV1 cases and welcomed that there had been no further cases detected since the last meeting. However, as there remain substantial populations in Northern Nigeria that are totally or partially inaccessible, the committee concluded that it is highly likely that polioviruses are still circulating in these areas. Reaching these populations is critically important for the polio eradication effort, but it is acknowledged that there are significant security risks that may pose 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 the committee urged that this innovative spirit be continued.

There was ongoing concern about the Lake Chad region, and for all the countries that are affected by the insurgency, with the consequent lack of services, and presence of Internally Displaced Persons (IDPs) and refugees. The risk of international spread from Nigeria to 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. CAR needs to maintain the current momentum, including further improvement to AFP surveillance and if feasible introduce environmental surveillance as is currently planned.

Equatorial Guinea 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.

Vaccine derived poliovirus

The committee was very concerned that two new outbreaks of cVDPV have been identified, one in Sokoto in northern Nigeria, and the second in Quetta Pakistan. The virus found in Sokoto was unrelated to that found in Borno. Both of these outbreaks highlighted the presence of vulnerable under immunized populations in countries with endemic transmission. The committee noted the response to these outbreaks, acknowledging that in both cases it had complicated the ongoing efforts to eradicate WPV1.

The Committee welcomed the provision of information by the Russian Federation at the meeting about the recent detection of VDPV in two children from the Chechen Republic, and also welcomed the surveillance and immunization activities taken to date in response. The Committee noted that the investigation by the Russian Federation had shown that one of the children was immunosuppressed. The Committee requested that the WHO European Regional office and WHO HQ should continue to work with the Russian Federation to confirm the classification of the viruses. Therefore as the risk of international spread is still being assessed, no recommendations regarding this situation have been made by the committee.

In Guinea, the most recent case of cVDPV had onset in December 2015, and based on the most recent assessments and the criteria of the committee, the country is no longer considered as infected, but remains vulnerable.

The committee also noted the detection of non-circulating VDPV in several other countries.

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 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 continued international spread of WPV1 between Pakistan and Afghanistan.
  • The persistent, wide geographical distribution of positive WPV1 in environmental samples and AFP cases in Pakistan, while acknowledging the intensification of environmental surveillance inevitably increasing detection rates.
  • The current special and extraordinary context of being closer to polio eradication than ever before in history, with the lowest number of WPV1 cases ever recorded occurring in 2016.
  • 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 WPV1, 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 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 from cVDPVs.