Objective To understand the epidemiological characteristics of
influenza outbreaks in
China from 2005 to 2013.
Methods The data of
influenza-like illness
outbreaks involving 10 or more cases were collected through
Public Health Emergency Management Information System and National
Influenza Surveillance Information System in
China,and the
influenza outbreaks were identified according to the
laboratory detection results. Descriptive epidemiological
analysis was conducted to understand the type/subtype of
influenza virus and outbreak
time,area,place and extent. Results From 2005 to 2013,a total of 3 252
influenza-like illness
outbreaks were reported in the mainland of
China,in which 2 915
influenza outbreaks were
laboratory confirmed,and influenza A(H1N1) pdm09
virus and
influenza B virus were predominant. More
influenza outbreaks were reported in the influenza A(H1N1)
pandemic during 2009-2010.
Influenza outbreaks mainly occurred during winter-spring,and less
influenza outbreaks occurred in winter and summer
vocations of
schools. More
influenza outbreaks were reported in southern provinces,
accounting for 79% of the total.
Influenza outbreaks mainly occurred in primary and
middle schools,where 2 763
outbreaks were reported,
accounting for 85% of the total. Averagely 30-99 people were involved in an outbreak. Conclusion A large number of
influenza outbreaks occur during
influenza season every year in
China,the predominant
virus type or subtype varies with
season. Primary and
middle schools are mainly affected by
influenza outbreaks.