title: Interpreting the transmissibility of measles in two different post periods of supplementary immunization activities in Hubei, China.
abstract: Although evidence has shown that supplementary immunization activity (SIA) campaigns greatly reduce the incidence of measles, their effects on disease transmissibility have seldom been monitored. A great decrease in the number of cases may be a false signal of early success towards measles elimination to policy makers. By interpreting the transmissibility in two different post-SIA periods in Hubei, China, the current study showed sustained measles transmissions despite a reduced number of cases. Two population-based cross-sectional serological surveys of measles antibodies were conducted in Hubei province in mid-2010 and mid-2011 after the implementation of SIAs. Immunoglobulin G (IgG) antibodies against measles were measured by enzyme-linked immunosorbent assay (ELISA). Based on the estimated age-specific susceptibility levels, the effective reproduction number (R), a key indicator of disease transmissibility, was determined by the next generation matrix in transmission model. The results revealed an overall IgG seroprevalence of 88.0% (95% confidence interval [CI]: 85.6-90.4%) and 89.6% (95%CI: 88.0-91.2%), respectively, in the two different periods. Comparatively lower seroprevalence rates were observed among children less than 24months of age and young adults 15 to 19years of age in 2011. The Rs were 0.76 and 1.53 for the two study periods. In conclusion, even though the incidence was reduced to below 1/100,000 in both 2010 and 2011, the reproduction number in 2011 indicates a high risk for sustained measles transmission. This finding was potentially due to a lower seropositivity rate among young adults that had not been covered in the first SIA. Thus, implementation of SIA targeted to appropriate age groups is recommended. Regular monitoring of seroprevalence is also suggested to track disease transmissibility and to align SIA with the appropriate age groups.
authors.affiliation: JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China; Clinical Trials and Biostatistics Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, China.
authors.forename: Ka Chun
authors.initials: KC
authors.lastname: Chong
authors.affiliation: Hubei Provincial Center for Disease Control and Prevention, Hubei, China.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China; Clinical Trials and Biostatistics Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, China.
authors.forename: Benny Chung Ying
authors.initials: BC
authors.lastname: Zee
authors.affiliation: JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Tongyong
authors.initials: T
authors.lastname: Luo
authors.affiliation: Hubei Provincial Center for Disease Control and Prevention, Hubei, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Greta Chun Huen
authors.initials: GC
authors.lastname: Tam
authors.affiliation: JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Katherine Min
authors.initials: KM
authors.lastname: Jia
authors.affiliation: JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China; Clinical Trials and Biostatistics Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, China.
authors.forename: Riyang
authors.initials: R
authors.lastname: Sun
authors.affiliation: JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China; Clinical Trials and Biostatistics Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, China. Electronic address: haitian.wang@gmail.com.
authors.forename: Maggie Haitian
authors.initials: MH
authors.lastname: Wang
authors.affiliation: Hubei Provincial Center for Disease Control and Prevention, Hubei, China. Electronic address: guanxh9999@163.com.
authors.forename: Xuhua
authors.initials: X
authors.lastname: Guan
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000096:biosynthesis*; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D017589:Immunization Programs; D007117:Immunization, Secondary; D007074:Immunoglobulin G / Q000096:biosynthesis; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008457:Measles / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control* / Q000635:transmission; D008458:Measles Vaccine / Q000008:administration & dosage*; D018103:Morbillivirus / Q000187:drug effects / Q000276:immunology*; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D008458:Measles Vaccine
keywords: Measles; Next generation matrix; Reproduction number; Supplementary immunization; Vaccination