Measles vaccine coverage estimates in an outbreak three years after the nation-wide campaign in China: implications for measles elimination, 2013

• Published in: BMC infectious diseases Vol. 15; no. 1; p. 23
• Main Authors: Ma, Chao, Li, Fangjun, Zheng, Xiang, Zhang, Hong, Duan, Mengjuan, Yang, Yanhua, Hao, Lixin, Su, Qiru, Rodewald, Lance, Guo, Bosong, Xiao, Shanliang, Wang, Huaqing, Li, Li, Li, Junhua, Luo, Huiming, Gao, Lidong
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 22.01.2015; BioMed Central
• Subjects: Adolescent; Child; Child Health Services; Child, Preschool; China - epidemiology; Disease Outbreaks - prevention & control; Female; Health Promotion; Humans; Infant; Male; Measles - epidemiology; Measles - prevention & control; Measles Vaccine - administration & dosage; Seroepidemiologic Studies; Vaccination - statistics & numerical data; China
• ISSN: 1471-2334; 1471-2334
• DOI: 10.1186/s12879-015-0752-z

China is approaching measles elimination, but indigenous measles still circulates. County L in China has reported measles-containing vaccine (MCV) coverage rates >95% since 2000. Despite high reported coverage, a large measles outbreak occurred among young children in L County. We measured MCV coverage using 5 different methods during an investigation on this outbreak and compared our estimates with reported rates. Reported coverage rates are determined by aggregating clinic-based data across the county: doses administered in each clinic divided by the number of children registered in each clinic. Our methods estimated coverage for the 2010-2012 birth cohort, and were (1) administrative method: doses administered in clinics divided by the birth cohort recorded in the Statistical Year Book, (2) house-to-house convenience-sample survey of children living near cases, (3) vaccination clinic records review, (4) determination of a convenience sample of measles outbreak cases' vaccination statuses and using the field vaccine efficacy outbreak equation to estimate population coverage, and (5) a seroprevalence survey using a convenience sample of residual blood samples from hospitals. The measles outbreak totaled 215 cases, representing an incidence of 195.8 per million population. Our estimated MCV coverage rates were: (1) administrative method: 84.1%-87.0% for MCV1 and 80.3%-90.0% for MCV2, (2) in-house survey: 83.3% of 9-17 month children received MCV1, and 74.5% of 24-47 month children received MCV2, (3) clinic record review: 85.5% of 9-17 month children received MCV1, and 73.2% of 24-59 month children received MCV2, (4) field VE method: 83.6% of 9-47 month children received one or more MCV doses, and (5) serology: seropositive rates were <80% in the 12-17 and 18-23 month age cohorts. Compared with reported coverage >95%, our 5 coverage assessments all showed substantially lower coverage. China should evaluate guidelines for reporting vaccination coverage and identify feasible improvements to the assessment methods.