Circulation of vaccine-derived poliovirus type 2 (cVDPV2) has been confirmed in Mozambique, according to the Global Polio Eradication Initiative (GPEI).

Mozambique/CIA
Mozambique/CIA

Officials report two genetically-linked circulating vaccine-derived poliovirus type 2 (cVDPV2) isolates were detected, from an acute flaccid paralysis (AFP) case (with onset of paralysis on 21 October 2018, in a six-year old girl with no history of vaccination, from Molumbo district, Zambézia province), and a community contact of the case.

According to GPEI:

Vaccine-derived polioviruses (VDPVs) are rare strains of poliovirus that have genetically mutated from the strain contained in the oral polio vaccine. The oral polio vaccine contains a live, attenuated(weakened) vaccine-virus. When a child is vaccinated,the weakened vaccine-virus replicates in the intestine and enters into the bloodstream, triggering a protective immune response in the child. Like wild poliovirus, the child excretes the vaccine-virus for a period of six to eight weeks. Importantly, as it is excreted, some of the vaccine-virus may no longer be the same as the original vaccine-virus as it has genetically altered during replication.

Image/CDC-/ Meredith Boyter Newlove, M.S., James Archer, M.S.
Image/CDC-/ Meredith Boyter Newlove, M.S., James Archer, M.S.

The GPEI and partners are working with country counterparts to support the local public health authorities in conducting a field investigation (clinical, epidemiological and immunological) and thorough risk assessment to discuss planning and implementation of immunization and outbreak response.

In January 2017, a single VDPV2 virus had been isolated from a 5-year old boy with AFP, also from Zambézia province (Mopeia district).  Outbreak response was conducted in the first half of 2017 with monovalent oral polio vaccine type 2 (mOPV2).

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