杭州地区不同谱系乙型流感病毒流行特征

Epidemiological characteristics of influenza B virus in different pedigrees in Hangzhou area

目的 了解杭州地区乙型流感病毒2个不同谱系的流行情况及对不同年龄段人群造成的影响。方法 收集杭州地区2013年10月—2019年9月流感样病例12 611例,real-time RT-PCR检测乙型流感病毒。对乙型流感病毒的流行模式和患者的年龄分布进行统计学分析。结果 2013年以来,杭州地区每年都有乙型流感病毒的流行,每个流感季以单一谱系的乙型流感病毒流行为主。Yamagata季和Victoria季的出现没有明显的规律性。仅2017年—2018年流感季出现了乙型流感病毒疫苗株与流行株不匹配的情况,但患者中位数年龄和发病率都没有显著的改变。单一谱系乙型流感病毒显著流行的流感季5岁~9岁年龄段人群发病率最高(P<0.001),2种谱系共同流行的流感季10岁~14岁年龄段人群发病率最高(P<0.001)。Victoria季乙型流感患者的中位数年龄最低(8岁,P<0.001),而Yamagata季65岁以上老人的发病率高于其他季节(P<0.001)。结论 乙型流感病毒不同流行模式下患者的年龄分布不同。应该根据不同的流行模式和主要影响的人群制定不同的乙型流感病毒防控措施。

Objective This paper aims to understand the prevalence of two different lineages of influenza B virus and their effects on different age groups in Hangzhou area. Methods A total of 12 611 influenza-like cases were collected in Hangzhou from October 2013 to September 2019. Real-time PCR was used to detect influenza B virus. The epidemic pattern of influenza B virus and the age distribution of patients were conducted for statistical analysis. Results Since 2013, influenza B virus has been prevalent in Hangzhou every year, and a single lineage of influenza B virus was dominant in each influenza season. The prevalence seasons of Yamagata and Victoria appear with no apparent regularity. A mismatch between the vaccine strain and the prevalent strain of influenza B virus was only observed in the 2017-2018 influenza season, but there was no significant change in the median age or incidence of patients. The incidence of influenza B virus was the highest in the 5-9 year age group(P<0.001) and in the 10-14 year age group(P<0.001) when the two lineages were prevalent. Victoria season had the lowest median age of influenza B patients(8 years, P<0.001), while Yamagata season had a higher incidence of persons over 65 years of age than other seasons(P<0.001). Conclusion The age distribution of patients infected by the influenza B virus was different among the different prevalence patterns. Information on the age distribution of patients infected by each influenza B virus lineage may be helpful for establishing differentiated influenza prevention and control strategies for each age group.