Analysis on etiological surveillance results of varicella in Beijing, 2017

ObjectiveTo understand the types and predominant types of varicella- zoster virus (VZV) in Beijing, 2017, and provide evidence for the prevention and control of varicella.

MethodsThe clinical vesicular fluid was collected from the varicella cases detected in outbreak of Beijing in 2017 for the identification of wild strains and vaccine strains of VZV with real-time PCR. The phylogenetic analysis on wild VZV in Beijing was performed based on the sequences of twenty-second open reading frame gene fragment (ORF).

ResultsAmong the 316 vesicular fluid specimens from varicella cases, 271 were positive for VZV. All of these strains belonged to wild VZV strains. The gene fragments were obtained for 240 of 271 wild strains. They belonged to 3 serotypes, including 234 clade 2 strains (97.50%), 3 clade 1 strains (1.25%) and 3 clade 4 strains (1.25%). Clade 2 strains was distributed in all of 16 districts of Beijing, and clade 1 and clade 4 strains were distributed in Xicheng and Daxing districts, respectively.

ConclusionThe varicella cases were mainly caused by clade 2 VZV in Beijing in 2017. It is necessary to strengthen the surveillance for new clade 1 and clade 4 VZV.