关键词: 流行性感冒, 流感病毒, 核酸检测

Abstract:

Objective　To analyze the epidemic patterns and pathogenic characteristics of influenza viruses in Haizhu District from 2021 to 2024, and to provide scientific basis and technical support for formulating influenza prevention and control measures. Methods　From March 2021 to December 2024, 5 120 throat swab samples from influenza-like cases were sent for nucleic acid testing in the Huizhou District Center for Disease Control and Prevention. The number of male samples tested was 2 698, and the number of female samples tested was 2 422. The age ranged from 1 day to 98 years old. The detection rates of influenza A/B viruses in the samples were analysed, and the population and seasonal distribution characteristics of different types of influenza viruses were compared. The statistical methodology employed the χ² test and the Bonferroni method for multiple comparisons. Results　A total of 5 120 throat swab samples were tested, and 2 578 samples were found to be positive for the influenza virus. The positive detection rate was 50.34%. Among them, the positive detection rate of influenza A was 68.11% (1 756/2 578), and the positive detection rate of influenza B was 31.89% (822/2 578). The predominant infection was caused by the influenza A virus, especially in 2023, when the positive detection rate of the influenza A virus reached as high as 75.12%. The positive detection rates in winter [63.86% (569/891)] and in spring [62.17% (1 047/1 684)] were both higher than those in summer and autumn. There was a statistically significant difference in the positive detection rate of influenza viruses between different seasons (χ²=1 313.806, P<0.001). The detection results of different seasonal influenza virus subtypes were analyzed. The proportion of type A (H1N1) influenza virus was the highest in spring (77.9%), while the detection rate of type A (H3N2) virus was higher in winter (37.65%). In autumn, there was a dual dominant trend of type A (H3N2) and type B (Victoria) subtypes, and the difference was statistically significant (χ²=490.000, P<0.001). The positive detection rates for males and females in the test samples were 50.22% (1,355/2,698) and 50.50% (1,223/2,422), respectively. For 939 of the samples, subtype detection of the influenza virus was conducted. The results showed that among all the subtypes, the detection rate of influenza subtypes in males was higher than that in females, and the difference was statistically significant (χ²=214.892, P<0.001). The highest positive detection rate of influenza virus nucleic acid was observed in the age group of 5 to <15 years old, with a detection rate of 73.55% (2 077/2 824), while the detection rate for the elderly in the ≥60-year-old age group was the lowest, only 8.14% (31/381). The detection rates of influenza A in all age groups were higher than those of influenza B. There was a statistically significant difference in the positive detection rate of influenza viruses between different age groups (χ²=12.095, P=0.017). The positive detection rate of influenza virus of the student group was higher than those of other groups. There was a statistically significant difference in the detection rate between different occupations (χ²=2 157.191, P<0.001). Conclusions　At the Haizhu District of Guangzhou City, the dominant influenza strains showed seasonal alternation in their prevalence from 2021 to 2024. The prevalence of type A influenza was generally higher than that of type B influenza. The detection rate was higher among children aged 5 to <15 years old and students. Continuous influenza pathogen monitoring should be carried out in schools. Through vaccination and health education measures, the monitoring and prevention of influenza outbreaks in kindergartens and primary and secondary schools should be strengthened.

Key words: Influenza, Influenza virus, Nucleic acid detection