| ObjectiveTo explore the protective effectiveness of pertussis vaccine for children in high incidence area of pertussis by case-control study,providing data for the vaccination of pertussis vaccine at the age of 6 in China.Methods(1)Descriptive epidemiology was conducted to analyze pertussis cases data from 2007-2017 in Liaocheng,Shandong province from the National Notifiable Infectious Disease Reporting System of Chinese Information System for Disease Control and Prevention,and the distribution of pertussis cases was described.(2)A case-control study of 1:1 match was designed to collect information on the characteris of subjects,clinical symptoms and signs,DTaP vaccination status,and exposure conditions.The distributional characteristics of pertussis cases were described and the protective effectiveness of pertussis vaccine at different ages and doses were analyzed.Results(1)A total of 1358 cases of pertussis were reported in Liaocheng durnng 2007-2017,0 dead.The average annual reported incidence was 2.12/100,000,ranging from 0.12/100,000 to 9.48/100,000 by year.The reported incidence was relatively stable belowl/100,000 during 2007-2012.100 cases of pertussis were reported.A total of 1258 cases of pertussis were reported duiring 2013-2017.The incidence of pertussis reported increased in 2013.The reported incidence was up to 4.35/100,000 in 2014 and then dropped to 2.71/100,000 in 2016.In 2017,China experiences a peak in nearly ten years in incidence with 9.48/100,000.The pertussis cases were reported throughout the year,and the distribution trend of pertussis was different.1201 cases were scattered children,accounting for 88.44%among all reported cases.The incidence rate of younger age group was higher,with the 1279 cases reported under 6 years old,accounting for 94.18%of all reported cases.The reported incidence was 32.31/100,000.(2)A total of 104 patients in the case group and 104 persons in the 1:1 matched control group were collected,with the same gender,and village or community,aging from 2 to 6 years old.There was no statistically difference on immunization history,parents'educational level,family income,children's classification,and per capita living areas.between the two groups.The results of 1:1 case-control study showed that the total protective effectiveness of pertussis vaccine was 86.70%(95%CI:53.50%-96.20%).The objects who had received more than 1 dose of DTaP were divided into different age groups to analyze.The protective effectiveness of 2,3,4,5 and 6 year old group were 89.40%,88.20%,87.60%,87.50%and 86.60%,respectively.The protective effectivenesses of pertussis vaccine under whole and partial immunization were 82.20%(95%CI:-9.00%-97.70%)and 88.70%(95%CI:49.30%-97.50%),respectively.Deleting the objects who were under whole immunization in the survey,the objects were divided into three groups according to the time interval between the inoculation time of the fourth dose of DTaP and the time of onset.The results showed that the protective effectivenesses of pertussis vaccine for<1,1-,2-,and 3 years after vaccination were 90.20%,86.70%,83.60%,and 83.30%,respectively.ConclusionThe case-control study of DTaP in Liaocheng showed that 4 doses of acellular pertussis vaccine has good protective effectiveness.The protective effectiveness of acellular pertussis vaccine decreased with increasing time after ivaccination.The protective effectiveness of whole immunization was higher than that of partial immunization. |
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