| Objective This study was conducted to analyze the epidemiological characteristics of mumps in Lu'an city from 2005 to 2015 and evaluate vaccine effectiveness of mumpscontaining vaccine(Mu CV),to provide basic data for strategy of mumps-containing vaccine in China.Methods Descriptive epidemiological method was used to analyze epidemic data of mumps of Lu'an city from National Notifiable Communicable Disease Report System from 2005 to 2015.We conducted a retrospective cohort study among all school students during a mumps outbreak to evaluate Mu CV effectiveness and identify risk factors contributed to this outbreak.Results The annual incidence rate during 2005 to 2015 for mumps in Lu'an city was increased generally.The average annual incidence was 29.5 per 100,000,and a total of 18,666 cases were reported.The number of mumps cases showed a seasonal distribution with a peaked season from April to July.The incidence of mumps showed three levels,namely high,medium and low.The incidence of mumps in Jin'an district and Yu'an district were higher than other counties,the annual incidence were 53.1 and 49.7 per 100,000,respectively.The average annual incidence of male(38.0 per 100,000)was higher than female(19.9 per 100,000).This data showed a high proportion of 76.8%(14,330)of mumps in the 4-14 age group,and 9-10 age group with highest incidence of 223 per 100,000.77.1%(14,386)cases were students.The annual vaccination coverage of Mu CV was more than 90.0%(from 2012 to 2016),much better than previous years(from 2008 to 2011).A total of 17 mumps outbreaks were reported from 2005 to 2016,accounted for 28.8% of all outbreaks.Fifteen(88.2%)outbreaks occurred in urban area,most of the outbreaks occurred in school and 16(94.1%)occurred in primary school.The outbreak field for evaluating the vaccine effectiveness(VE)occurred in October 14 th,2016 to January 20 th,2017 which lasted more than 3 months.Totally,we identified 97 clinical mump cases,and the overall attack rate(AR)was 7.5%.9.3%(9 of 97)of patients experienced complication including meningitis(3 cases),orchitis(3 cases)and hearing damage(3 cases).A total of 1140 students completed questionnaires.The response rate for the questionnaire was 96.1%(1140 of 1186).In this school setting,80.6%(919 of 1140)students had received at least 1 dose of Mu CV with 65.5%(747 of 1140)receiving one dose,and 9.4%(107 of 1140)students were unvaccinated.78.4% students received MMR vaccine among the students who received 1 dose of Mu CV.14.4% patients were not isolated.In the final model of the multiple logistic regression analysis showed that only unvaccinated Mu CV(OR=3.55,95% CI: 2.02-6.18)and took school bus(OR=2.20,95% CI: 1.37-3.53)were significant risk factors of mumps outbreaks.A total of 991(included 89 cases)individuals were included in the VE evaluation after excluding 147 respondents with pervious mumps history or unknown immunization history.The VE for Mu CV(?1 dose)was 62%(95% CI: 41%-76%),where VE for 1 dose was 59%(95% CI: 36%-74%)and 2 doses reached to 76%(95% CI: 49%-89%).The VE for 1 dose Mu CV tended to wane with time,where VE for less than 5 years was 82%,5-9 years was 60%,and more than 10 years declined to 41%.The VE for 2 doses(100%)of MMR vaccine was slightly better than 1 dose(62%).The VE for 1 dose of MMR vaccine also waned with time,where the VE within 5 years after vaccination was 81%(95% CI: 37%-94%)and the VE over 5 years waned to 59%(95% CI: 34%-75%).Conclusion The incidence of mumps in Lu'an city was much higher than national level,we should take targeted intervention measures to control the high incidence.Mumps in Lu'an showed a seasonal distribution with peaked season from April to July,and showed a high proportion in the 6-10 age group and urban area.The VE for Mu CV(?1 dose)was 62%,where VE for 1 dose was 59% and 2 doses reached to 76%.The VE for 1 dose Mu CV tended to wane with time,where the VE within 5 years after vaccination was more than 80% but the VE over 5 years waned to 59%.Vaccination strategy of mumps in China should be reevaluated timely,and at least 2 doses of Mu CV with appropriate intervals should be considered. |
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