分析雅安市2019－2024监测年度流行性感冒的流行特征、病毒型别分布及人群感染规律，为精准流感防控提供科学依据。

收集雅安市两家国家级哨点医院2019年3月至2025年2月流感监测数据(剔除2020年度疫情防控期间零检出数据)，采用逆转录聚合酶链反应(reverse transcription-polymerase chain reaction, RT-PCR)进行病毒分型鉴定，应用χ²检验比较不同年度、季节、人群阳性检出率差异。

共纳入13 454例样本，阳性2 535例(18.84%)，年际间差异显著(P<0.001)，2023年度阳性803例(29.82%)。病毒分型以季节性H3N2亚型流感病毒〔Seasonal influenza A(H3N2)subtype,季H3型〕1 411例(55.66%)，其次为乙型流感病毒Victoria系(Influenza B virus Victoria lineage, BV型)1 725例(28.60%)和2009甲型H1N1亚型流感病毒〔2009 pandemic influenza A(H1N1)virus，新甲H1型〕399例(15.74%)，未检出乙型流感病毒Yamagata系(Influenza B virus Yamagata lineage, BY型)。季节分布呈秋季1 020例(27.54%)和冬季792例(24.00%)双峰特征，夏季最低255例(7.93%)，差异有统计学意义(P<0.001)。5~14岁年龄组阳性检出1 303例(30.23%)；学生1 207例(33.07%)、教师15例(37.50%)阳性率显著高于其他职业(P<0.001)，校内阳性1 711例(25.76%)显著高于校外824例(12.09%)(P<0.001)。

雅安市流感在秋季、冬春季均为高发，以秋季高峰最为显著。季H3型、BV型、新甲H1型交替流行特征，学生和教师为高风险人群。建议针对5~14岁学龄儿童、教师及托幼儿童优先接种疫苗，加强学校等重点场所晨午检和因病缺勤追踪，建立"型别-季节"双维度预警系统。

To clarify the epidemiological characteristics, viral subtype distribution and population infection patterns of influenza in Ya′an City during surveillance years 2019-2024, so as to provide scientific evidence for targeted prevention and control strategies.

Influenza surveillance data from March 2019 to February 2025 were collected from two national sentinel hospitals in Ya′an City, with zero-positive data generated during epidemic prevention and control in 2020 excluded. Reverse transcription-polymerase chain reaction (RT-PCR) was performed for viral subtyping identification. The chi-square (χ²) test was adopted to compare differences in positive detection rates across different years, seasons and populations.

A total of 13, 454 samples were included, with 2, 535 positive cases (18.84%). The annual differences were significant (P<0.001), and 803 positive cases (29.82%) were detected in 2023. Virus typing was dominated by seasonal influenza A(H3N2) subtype (seasonal H3) with 1, 411 cases (55.66%), followed by influenza B virus Victoria lineage (BV lineage) with 1, 725 cases (28.60%) and 2009 pandemic influenza A(H1N1) virus (novel H1N1) with 399 cases (15.74%); influenza B virus Yamagata lineage (BY lineage) was not detected. The seasonal distribution showed a bimodal pattern, with 1, 020 cases (27.54%) in autumn and 792 cases (24.00%) in winter, and the lowest number of 255 cases (7.93%) in summer; the difference was statistically significant (P<0.001). The 5-14 years age group had 1, 303 positive cases (30.23%); the positive rates among 1, 207students(33.07%) and15 teachers (37.50%) were significantly higher than those in other occupations (P<0.001). The positive rate in the school setting 1, 711 cases( 25.76%) was significantly higher than that outside school 824 cases(12.09%) (P<0.001).

Influenza epidemics in Ya′an City prevail in autumn, winter and spring, with the most prominent peak occurring in autumn. Alternating circulation of seasonal H3, BV and pdm09 A/H1N1 strains is identified, and students and teachers constitute high-risk populations. It is recommended to prioritize influenza vaccination for school-aged children aged 5-14 years, teachers and preschool children, strengthen morning and afternoon temperature checks as well as absence tracking due to illness in key settings such as schools, and establish a two-dimensional early warning system covering viral subtype and seasonal dynamics.