The Guardian (Nigeria)

Nigeria, Yemen, DR Congo account for more than 85% of vaccine- derived polio cases in 2022

• Blames outbreaks on inaccessib­ility, insecurity, high concentrat­ion of zero dose children, population displaceme­nt • WHO says cases in Algeria linked to viruses circulatin­g in Nigeria • Says cases in Benin, Ghana, Togo, Côte d’ivoire resulted from reinf

- By Chukwuma Muanya

AWorld Health Organisati­on ( WHO) committee on polio, yesterday, said Northern Yemen, eastern Democratic Republic of Congo and northern Nigeria continue to account for more than 85 per cent of the global circulatin­g Vaccine Derived Polio Viruses ( CVDPV2) caseload.

A vaccine- derived poliovirus ( VDPV) is a strain related to the weakened live poliovirus contained in oral polio vaccine ( OPV). If allowed to circulate in under- or unimmunise­d population­s for long enough, or replicate in an immuno- deficient individual, the weakened virus can revert to a form that causes illness and paralysis.

The thirty- third meeting of the Emergency Committee under the Internatio­nal Health Regulation­s ( 2005) ( IHR) on the internatio­nal spread of poliovirus convened by the WHO DirectorGe­neral, in a statement, said there have been four new countries reporting CVDPV2 - Algeria, Israel, the United Kingdom of Great Britain and Northern Ireland and the United States of America. It said the viruses detected in the latter three countries are geneticall­y linked indicating long- distance internatio­nal spread through air travel has occurred.

The Emergency Committee reviewed the data on wild poliovirus ( WPV1) and CVDPV in the context of global eradicatio­n of WPV and cessation of outbreaks of CVDPV2 by end of 2023.

The committee said the virus in Algeria is geneticall­y linked to viruses circulatin­g in Nigeria and is therefore an importatio­n due to internatio­nal spread. “Furthermor­e, the detection of CVDPV2 in Benin, as has been seen in Ghana, Togo and Côte d’ivoire appears to have resulted from reinfectio­n caused by new internatio­nal spread from Nigeria,” it noted.

The WHO committee said three new countries have reported CVDPV1 - Democratic Republic of the Congo, Malawi and Mozambique.

The committee noted that much of the risk for CVDPV outbreaks could be linked to a combinatio­n of inaccessib­ility, insecurity, a high concentrat­ion of zero dose children and population displaceme­nt. These, it said, have been most clearly evidenced in northern Yemen, northern Nigeria, south central Somalia and eastern DRC. Despite the ongoing decline in the number of cases and lineages circulatin­g, the recent episodes of internatio­nal spread of CVDPV2 indicate the risk remains high.

Although encouraged by the reported progress, 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 recognised the concerns regarding the lengthy duration of the polio PHEIC and the importance of exploring alternativ­e IHR measures in the future but concluded that there are still significan­t risks as exemplifie­d by the importatio­n and continued transmissi­on of virus in Malawi and Mozambique.

The Committee recognises that border vaccinatio­n may not be feasible at very porous borders in Africa but was concerned by the lack of synchronis­ation and cross border coordinati­on in response to the WPV1 importatio­n in southeast Africa. Outbreak response assessment­s are being carried out currently and urged the countries most directly involved in the response – Malawi and Mozambique - to facilitate these assessment­s. The committee also noted with concern that most AFP cases were being detected during campaigns and more systematic surveillan­ce efforts are required including training of clinicians to identify and respond to AFP cases. Noting the acute humanitari­an crisis still unfolding in Afghanista­n, the committee urged that polio campaigns be integrated with other public health measures wherever possible including malnutriti­on screening, vitamin A administra­tion and measles vaccinatio­n. The committee also strongly encouraged house to house campaigns be implemente­d wherever feasible as these campaigns enhance identifica­tion and coverage of zero dose and under- immunised children.

In Pakistan, the opportunit­y to interrupt polio transmissi­on in the coming low season, noting that the reported cases are geographic­ally limited to south KP with positive environmen­t isolates detected elsewhere in KP, Punjab and Sindh. The committee urged Pakistan to grasp the upcoming opportunit­y.

The committee noted the situation in northern Yemen with concern where it is estimated several million children have still not been accessed for immunizati­on. The committee strongly encouraged more urgent dialogue with all relevant stakeholde­rs to enable children to be vaccinated and protected.

The CVDPV2 outbreaks in Jerusalem, London and New York highlight the importance of sensitive polio surveillan­ce, including environmen­tal surveillan­ce, in all areas where there are high risk sub- population­s, and the committee urges all countries to take heed of the lesson learnt through this event and take steps to improve polio surveillan­ce everywhere that such risks exist.

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