The thirty-third meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) on the international spread of poliovirus was convened by the WHO Director-General on 12 October 2022 with committee members and advisers attending via video conference, supported by the WHO Secretariat. The Emergency Committee reviewed the data on wild poliovirus (WPV1) and circulating vaccine derived polioviruses (cVDPV) in the context of global eradication of WPV and cessation of outbreaks of cVDPV2 by end of 2023. Technical updates were received about the situation in the following countries and territories: Afghanistan, Algeria, Malawi, Mozambique, Pakistan, the United Kingdom of Great Britain and Northern Ireland, the United States of America and Yemen.

Wild poliovirus

The committee was concerned that since its last meeting in June 2022, Pakistan has reported twelve WPV1 cases all from southern Khyber Pakhtunkhwa (KP) province in Pakistan. Nine cases were from the district of North Waziristan, two from Lakki Marwat and one from South Waziristan bringing the total number of cases in 2022 in Pakistan to 20. Furthermore, there have been 31 additional positive environmental samples detected in districts in KP, Punjab, Sindh and Islamabad, bringing the total to 33 (65 isolates detected in 2021). However, no human polio case has been reported outside of southern KP. The committee noted that the key challenges which are driving transmission in southern KP include the complex security situation leading to inadequate campaign quality and missed children, community resistance (eg fake finger-marking without vaccination, refusals due to various reasons, vaccination boycotts), lack of female frontline workers, weak health infrastructure and service delivery, and sub-optimal routine immunization. Another challenge faced in the most recent campaign was the impact of widespread flooding.

The committee noted that although the ongoing WPV1 outbreak in Pakistan led to a risk of spillover into Afghanistan, there is no evidence of cross-border transmission to date in 2022. Two cases have been reported to date in 2022, one in Paktika province and a second in Kunar province in the East. The polio programme in Afghanistan has gained and sustained access across the country including nearly 3 million children previously inaccessible for almost four years. There remain approximately half a million missed children mostly in the southern region, due to the continued implementation of the mosque to mosque campaign modality. There are also clusters of refusals mainly in the South-East and East regions. Pockets of insecurity pose a threat to polio workers noting that eight vaccinators were killed on 24 February 2022 during a campaign.

The committee was very concerned about continued WPV1 transmission in the Tête province of northern Mozambique. Genetic sequencing confirms that all the viruses are related indicating the outbreak is due to international spread through a single importation event. While the quality of the rounds in the multi-country immunization response is improving, coverage has been insufficient to halt transmission. Furthermore, while synchronization of activities has been agreed upon by all countries involved in the response, it has yet to be implemented in practice. Zimbabwe has yet to conduct any immunization response although it shares a border with the outbreak zone in Tête. Surveillance activities have also been insufficiently coordinated across borders, with Mozambican citizens coming to Malawi for medical care for acute flaccid paralysis and being notified in Malawi rather than Mozambique. Surveillance in Mozambique relies on case finding during campaigns with a lack of active surveillance between campaigns. Other challenges include multiple emergencies, frontline worker fatigue and and high population movement within the subregion.

The committee noted with concern that several frontline health workers were killed in Afghanistan in February 2022, and commended the dedication of health care workers in all countries who are responding to these outbreaks.

Source: World Health Organization