Analysis on acute flaccid paralysis case surveillance after polio vaccination schedule change in Hebei province

Objective To analyze the epidemiological characteristics of acute flaccid paralysis (AFP) in children aged 15 years before and after the change of polio vaccination schedule in Hebei province, and explore measures for AFP control and prevention.

Methods The incidence data of AFP cases in children aged 15 years during May in 2015-April in 2016 (pre-change period) and May in 2016-April in 2017 (post-change period) in Hebei province were collected from the AFP surveillance system and analyzed by using software SPSS 21.0. The chi square test and the Fisher's exact method were used to compare the rate and constituent ratio.

Results During the two period, 312 and 361 AFP cases were reported respectively, the cases mainly occurred in summer and autumn. The disease spectrum was mainly Guillain-Barre syndrome, but hand-foot-mouth and spinitis cases increased. The incidence rates were 2.38/100 000 and 2.58/100 000, respectively. AFP cases were mainly distributed in children aged 0–4 years. The proportion of residual paralysis was 11.86% and 17.45%, respectively; The isolation rate of polio virus was 2.56% and 1.66%, respectively, polio viruses typeⅠand Ⅲ were predominant. The isolation rate of non-polio enterovirus were 19.23% and 12.74%.

Conclusion The features of incidence, seasonal, area and population distributions and symptom spectrum of AFP cases did not change greatly before and after the change of polio vaccination schedule in Hebei. Non-polio enterovirus isolation rate decreased significantly, but the proportion of residual paralysis increased, predominant type Ⅰ strain type was replaced by type Ⅲ strain.