[Seasonal, avian and pandemic influenza: are we prepared?]

China experienced a very high and severe influenza seasonal epidemics during the past winter and spring of 2017-2018 season. This year of 2018 is the 100(th) anniversary of the 1918 "Spanish influenza" pandemic, a series of papers under the topic "One Hundred Years of Influenza Pandemics" are produced to demonstrate the impact, characteristics and responses of the past influenza pandemics in global and China, to review the progress and experiences of influenza surveillance, prevention and control strategies, vaccination and antivirus in China, and to discuss the gap and challenges of the prevention, control and response to the seasonal influenza, human avian influenza infection and influenza pandemics. We hope this series could help to raise the awareness of the seasonal and pandemic influenza in publics, and to improve the pandemic preparedness in China.