A cross-sectional investigation on the control effect of varicella vaccination on the outbreak of varicella in Minhang District of Shanghai / 复旦学报（医学版）

ABSTRACT

Objective To analyze the changes of varicella outbreak in Minhang District before and after practicing "the varicella emergency vaccination implementation program (2013-2014 trial version),Shanghai",and to evaluate the effects of live attenuated vaccine against varicella.Methods We used cross-sectional investigation to collect monitoring data of vaticella outbreak recorded in "China Information System for Disease Control and Prevention".The observation periods before and after the implementation of the program were during 2012-01-01 to 2013-06-30 and during 2013-07-01 to 2014-12-31.Results Before the implementation of the program,14 cases of varicella epidemic were reported in Minhang District.All cases were up to the outbreaks in the epidemic,the longest duration was 82 days,the average duration continued was 50.86 days (912/14),the average cumulative generation was 2.42 generations (50.86/21),the total number of people was 159,the total incidence rate was 1.26％ (159/12 625),the class incidence rate was 9.09％ (159/1 750),the average number of people was 11.36 (159/14),the average number of class was 3.21 (45/14).After the implementation of the program,169 cases of the varicella epidemic were reported in Minhang District,only 22 cases rose to the outbreaks in the epidemic,the longest duration was 66 days,the average duration continued was 41.32 days (909/22),the average cumulative generation was 1.97 generations (41.32/21),the total number of people was 200,the total incidence rate was 1.10％ (200/18 200),the class incidence rate was 8.38％ (200/2 387),the average number of people was 9.09 (200/22),the average number of class was 2.50 (55/22);Although the varicella epidemic in the total outbreaks had significantly increased in Minhang District before and after emergency implementation,but the varicella outbreak in the varicella epidemic significantly decreased,the total incidence rate,the class incidence rate,the longest duration,the average duration,the average cumulative generation,the average number of people and the average number of class had decreased in varying degrees.There is statistical difference between the average duration before and after the implementation (x2 =4.06,P＜0.05).Conclusions Emergency vaccination of varicella vaccine in high risk population can effectively control the spread of epidemic situation and reduce the possibility of secondary transmission.