Prevalence of influenza A(H1N1) viruses in Hangzhou after 2009 pandemic and characteristics in lineage changes
10.3760/cma.j.cn112309-20211222-00429
- VernacularTitle:大流行后杭州地区甲型H1N1流感病毒的流行及其支系更替特征分析
- Author:
Jun LI
1
;
Gang ZHAO
;
Xinfen YU
;
Xiaofeng QIU
;
Xiao XIAO
;
Yinyan ZHOU
;
Guozhong ZHANG
Author Information
1. 杭州市疾病预防控制中心卫生检验中心，杭州 310021
- Keywords:
Influenza virus;
A(H1N1)pdm09;
Hemagglutinin;
Lineage
- From:
Chinese Journal of Microbiology and Immunology
2022;42(8):609-614
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To study the epidemiological features of local influenza A(H1N1)pdm09 epidemic strains through analyzing the changes in lineages and to analyze how well the vaccine strains were matched to the circulating strains in Hangzhou.Methods:Of 1 112 clinical specimens from laboratory-confirmed A(H1N1)pdm09 infections in Hangzhou in consecutive seasons from 2009 to 2020, 208 (18.7%) with high viral load (Ct value <30) were randomly selected from 10 influenza epidemics for full-length hemagglutinin gene ( HA) gene sequencing. Genetic variation, evolution and lineage changes of these representative local strains were analyzed by comparison with vaccine strains and reference strains. Results:Since the 2009 pandemic, A(H1N1)pdm09 had become one of the predominant viruses causing seasonal influenza and been reported to co-circulate with influenza A(H3N2) and influenza B viruses in Hangzhou in the past decade. It caused 10 local influenza epidemics in the 12 consecutive seasons from 2009 to 2020. HA gene sequencing revealed complex sources and rapid variation of the local A(H1N1)pdm09 strains. The main epidemic strains often genetically drifted from the recommended northern hemisphere vaccine strains due to lineage changes. Conclusions:This study suggested that it was essential to update the recommended vaccine strains year by year. Besides, enhanced periodic monitoring of influenza A(H1N1)pdm09 strains circulating in the region was important for the prevention and control of influenza A(H1N1)pdm09 infection in the next epidemic season.
