2016—2020年浙江省衢州市流感监测结果分析

目的了解2016—2020年浙江省衢州市流行性感冒(简称流感)流行特征,分析流感样病例(influenza-like illness,ILI)与流感病毒检测阳性率的关系,为优化流感防控提供科学依据。方法按照国家流感监测方案,对2016—2020年衢州市国家级流感监测哨点医院报告ILI及流感病原学监测结果进行统计和分析。结果2016—2020年衢州市共报告ILI 41995例,占就诊总人数的4.41%,2016—2019年,ILI%有上升趋势(χ2趋势=84.369,P<0.001)。2020年ILI%显著低于2016—2019年平均ILI%(4.06%vs.4.47%,χ2=33.657,P<0.001)。报告ILI以0~4岁组为主(19308例)占45.98%,0~14岁组(26617例)占63.38%。共采集ILI样本5589份,总阳性率为17.07%(954/5589),其中男性阳性率18.12%(463/2555),女性阳性率16.18%(491/3034),性别间阳性率差异无统计学意义(χ2=3.680,P=0.055)。2016—2020年样本阳性率分别为14.95%(164/1097)、20.02%(211/1054)、14.11%(152/1077)、33.36%(373/1118)、4.34%(54/1243),总体上呈下降趋势(χ2=8.656,P=0.003)。2016—2019年每年冬春均有流行高峰,主要集中在每年的11月至次年2月,2018年夏季出现流行高峰。病原以甲型H3N2亚型为主,占42.14%(402/954)。不同年龄组中,流感病毒阳性率显著不同(χ2=104.981,P<0.001),0~4岁、5~14岁、15岁及以上三个年龄组ILI数与病毒核酸检测阳性率呈正相关,相关系数均有统计学意义(Spearman相关系数分别为0.716、0.905、0.839,P值分别为0.009、<0.001、0.001)。结论2016—2020年衢州市以甲型流感病毒为主,基本呈冬春季高发,偶有夏季高发,发病人群以14岁以下儿童为主,建议做好此类人群流感防控。ILI数与病毒核酸检测阳性率呈正相关。

Surveillance results of influenza in Quzhou City,Zhengjiang Province, 2016-2020

Objective To study the epidemic characteristics of influenza in Quzhou City from 2016 to 2020, to analyze the relationship between influenza-like illness (ILI) cases and positive rate of influenza virus detection, and to provide a scientific basis for effective influenza prevention and control. Methods According to the national influenza surveillance program, we statistically analyzed the data about ILI cases reported by a national sentinel hospital and pathogen surveillance results from Quzhou Municipal Center for Disease Control and Prevention in Quzhou City from 2016 to 2020. Results A total of 41,995 ILI cases were reported in Quzhou City from 2016 to 2020, accounting for 4.41% (ILI%) of the total number of medical visits. The ILI% in 2016-2020 showed an upward trend (χ²_trend=84.369, P<0.001). The ILI% in 2020 was significantly lower than the average ILI% in 2016-2019 (4.06% vs. 4.47%, χ²=33.657, P<0.001). Most ILI cases reported were from the 0- age group and the 0-14 age group, accounting for 45.98% (n=19,308) and 63.38% (n=26,617), respectively. A total of 5,589 ILI samples were collected, with a total positive rate of 17.07% (954/5,589). The positive rates in males and female were 18.12% (463/2,555) and 16.18% (491/3,034), respectively, and no statistically significant difference was found in the positive rate between the genders (χ²=3.680, P=0.055). The positive rates of samples in 2016-2020 were 14.95% (164/1,097), 20.02% (211/1,054), 14.11% (152/1,077), 33.36% (373/1,118) and 4.34% (54/1,243), respectively, showing an overall decreasing trend (χ²=8.656, P=0.003). The epidemic peak occurred in winter and spring of each year from 2016 to 2019, mainly from November to February of next year, and there was an epidemic peak in summer of 2018. The dominant strain was subtype A (H3N2), accounting for 42.14% (402/954). The positive rate of influenza virus was significantly different in different age groups (χ²=104.981, P<0.001). The numbers of ILI cases in the age groups 0-4 years, 5-14 years and ≥15 years were positively correlated with the positive rate of virus nucleic acid test, and the correlation coefficients were statistically significant (Spearman r=0.716, P=0.009; Spearman r=0.905, P<0.001; Spearman r=0.839, P=0.001). Conclusion The influenza A virus was the dominant species in Quzhou City from 2016 to 2020, with a high incidence in winter and spring, and occasionally in summer. Most ILI cases were children under 14 years old. It is suggested that influenza prevention and control should be strengthened among children below 14 years old. The number of ILI cases was positively correlated with the positive rate of virus nucleic acid test.