Epidemiology of influenza virus reinfection in Guangxi, China: a retrospective analysis of a nine-year influenza surveillance data
Jing Wang, Lina Jiang, Yunan Xu, Weitao He, Chao Zhang, Fuyin Bi, Yi Jer Tan, Chuanyi Ning
Abstract
BACKGROUND: Epidemiological characteristic profile of the reinfection of the influenza virus has not been well described. METHODS: This study included all influenza cases of Guangxi, China from January 2011-December 2019 that were recorded in the National Notifiable Infectious Disease Reporting Information System (NIDRIS) within 24 hours after diagnosis. RESULTS: A total of 53,605.6 person-months and the median time of 8.7 months were observed for reinfection. The median age at the first influenza virus infection was 4.5 (interquartile range=2.0-7.5) years. The cumulative reinfection incidence was 2% at 6 months, 4% at 12 months, 5% at 24 months, and 7% after 59 months. Living in the rural area (hazard ratio [HR]=1.37 [95% confidence interval (CI), 1.29-1.45]), age ≤6 years (HR=11.43 [95% CI, 9.47-13.80]) were independent risk factors associated with influenza reinfection. Among 49 patients experiencing two laboratory tests, 32 patients (65.3%) were found to be infected with different virus types. The interval between two consecutive laboratory-confirmed episodes of the four groups differed (p=0.148): the maximum was 72.9 months and the minimum was 1.2 months. CONCLUSIONS: The reinfection of the influenza virus in Guangxi was independently and positively associated with living the rural area and younger age. The unusually high frequency of reinfection points to a need for further prospective longitudinal studies to better investigate the sufficient impact on different subtypes.