NIV test confirms Meghalaya child inflicted with vaccine derived polio, not wild polio virus

Officials in the state health department said the confirmation put to rest the possibility of jeopardising India's status as polio-free country, which it acquired in 2014.

Guwahati: Tests of samples by the National Institute of Virology, Mumbai has confirmed that the two-year-old child in Meghalaya's Garo Hills was inflicted with vaccine derived polio virus and not wild polio virus as initially suspected.

Officials in the state health department told DH on Friday the confirmation put to rest the possibility of jeopardising India's status as polio-free country, which it acquired in 2014.

"As per the protocols, two stool samples were collected from the affected child and sent to the Institute of Serology, Kolkata for laboratory testing. Later, sequencing was done at NIV Mumbai. Laboratory results reported the child as Virus Derived Polio Virus (VDPV) case and not wild polio virus," said a note shared by the state health department.

The two-and-half-year boy from Jengrip village in West Garo Hills district was admitted to a hospital in neighbouring Assam's Goalpara district on June 22 with symptoms of limping in his right leg. This triggered fears of fresh emergence of polio cases, a public health issue India struggled with for decades before a mass polio immunization campaign was taken up.

The VDPV is a strain related to the weakened version of the live poliovirus contained in the oral polio vaccine. The oral vaccines are by and large safe but in rare cases can trigger the disease in children with weak immune systems.

"VDPVs are extremely rare and are detected in children with immunodeficiency or in populations with low levels of immunization. Laboratory results showed that the child had good immunity and no evidence of immune deficiency. The most important strategy for prevention of emergence of VDPV is achieving and maintaining high routine immunization coverage with OPV and Inactivated Polio Vaccine (IPV) doses among children," said the health department.

A detailed epidemiological investigation by a team of the health department and WHO found that the immunization coverage was very poor in the Jengrip village. "The child has not received any routine immunization doses, no IVP doses and received only two Oral Polio Virus doses during the National Immunization Day. The final classification will be done by the Polio Expert Committee at the national level. As of now, the child is not immunocompromised and there is no evidence of viral circulation in the community. There is a need to strengthen acute flaccid paralysis (AFP) and routine immunization surveillance in West Garo Hills districts and adjoining districts of Meghalaya and Assam," said the note.