An epidemiological investigation on vaccine-hypervariable poliovirus in a case with acute flaccid paralysis in Zhejiang Province / 预防医学

ABSTRACT

Abstract@#Vaccine-hypervariable poliovirus type Ⅲ was detected in an acute flaccid paralysis infant at age of 6 months in Zhejiang Province in June, 2021, and the isolated and incubated virus had six nucleotide variations in the VP1 region as compared to the poliovirus Sabin vaccine strain. The infant had a history of three-dose poliovirus vaccination, and grade 2 muscle strength of the left upper limb upon onset. He was clinically diagnosed with cellulitis of the left shoulder, and recovered to normal following treatment. No abnormality was detected in the nervous system, and the infant was cured and discharged from hospital. No vaccine-hypervariable poliovirus was detected in subsequent infant' clinical samples or in close contacts, and no similar cases were identified during the active case detection by county/district medical institutions and among community populations. Since the infant did not present poliomyelitis-related clinical symptoms caused by vaccine-hypervariable poliovirus, poliomyelitis was excluded. The vaccine-hypervariable poliovirus was not spread because of timely identification and effective responses, suggesting the urgent need to maintain the sensitivity of the acute flaccid paralysis surveillance system and improve the coverage of poliovirus vaccination, so as to inhibit the transmission of poliovirus.