In the 2017-2018 season, influenza-like illness (ILI) activities began to increase in November, and reached a long period of high activity nationwide in January and February, and continued until the end of March. The peak of ILI was 7.5%, the highest percentage since the 2009 influenza pandemic (7.7%). Influenza-like illness (ILI) reached or exceeded the national benchmark for 19 weeks, making 2017-2018 one of the longest seasons in recent years.