Impact of enterovirus 71 vaccine vaccination on incidence of hand, foot and mouth disease among children in China mainland: an interrupted time series analysis

  Objective  To analyze the impact of enterovirus 71(EV71) vaccine vaccination on the incidence of hand, foot and mouth disease (HFMD) among children under five years old in China mainland and to provide evidences for the prevention and control of HFMD.

  Methods  The data on monthly incidence of HFMD among children under five years in China mainland from January 2015 through December 2017 were extracted from the Public Health Database established by Chinese Center for Disease Control and Prevention. The data were categorized into five one-year age groups and analyzed using interrupted time series analysis with Stata/SE 15 software.

  Results   The age-group specific HFMD incidence rate (1/100 000) during the two periods (January 2015 – July 2016 and August 2016 – December 2017) before and after the implementation of EV71 vaccine vaccination were not significantly different for each of the five one-year age groups (122.54 vs. 117.96, 350.03 vs. 290.64, 239.99 vs.192.61, 213.53 vs. 179.21, and 119.49 vs. 104.37 for the age groups of 0, 1, 2, 3, and 5 years, respectively; all P > 0.05). During the period before EV71 vaccine vaccination, an significantly increasing trend in monthly age-group specific HFMD incidence rate was observed among the children (P < 0.05 for all), except for among those of aged 0 year; the slope for the incidence rate increment was the highest among the children aged 3 years. After the vaccination, the most significantly notable immediate drop by 118.107/100 000 in monthly HFMD incidence rate was observed in the children aged 0 year (P = 0.044), followed by that by 101.135/100 000 in the children aged 3 years (P = 0.045); whereas, there was no significant change in the immediate monthly age-group specific HFMD incidence rate among the children of other ages (all P > 0.05). The analysis revealed a significantly declining trend in the monthly HFMD incidence rate after the vaccination only for the children aged 2, 3, and 5 years (P < 0.05).

  Conclusion  EV71 vaccine vaccination could decrease HFMD incidence significantly among the children aged two to five years. Preventive strategies other than vaccine vaccination should be promoted among the children under two years old.