[Epidemiological characteristics of influenza in Guangdong province, during winter of 2017-2018]

Objective: To understand the epidemiological characteristics of influenza in Guangdong province, during the winter of 2017-2018, to provide evidence for response to the diversity of influenza, in different seasonal patterns. Methods: Data on weekly influenza surveillance from January 2016 to April 2018, were collected in Guangdong. Information on patients with Influenza-like illness (ILI), on influenza virus positive rates and on outbreaks during the winter of 2017 to 2018, was analyzed and compared with those in spring of 2016 and summer of 2017. χ(2) test and Fisher exact test were used. Results: In the above said winter, the average percentage of visits for ILI in 28 hospitals where sentinel surveillance program had been set, was 4.99% (157 235/3 149 656), which was above the level of the same period in the previous five years. The positive rates of influenza virus among samples collected from ILI outpatients and hospitalized cases under severe acute respiratory infection (SARI) were 28.33% (2 137/7 543) and 14.93% (256/1 715), with the proportions of B (Yamagata) as 70.43% (1 505/2 137) and 73.05% (187/256) respectively. A total of 257 influenza outbreaks were reported in the winter period, with 82.49% (212/257) occurred in elementary schools. Cases aged 6-14 years occurred in winter and spring appeared of having higher positive rate than those seen in summer (P<0.05) whereas elderly cases aged 60 and above showed higher positive rate in summer than those in winter and spring two seasons (P<0.05). Conclusions: Epidemiological characteristics of influenza appeared in Guangdong province, during the winter from 2017 to 2018, were correlated to Influenza B (Yamagata). Capacity on the implementation of surveillance programs and on the coverage of vaccination should be improved and increased in order to control influenza in different epidemic seasons, in Guangzhou.