Chuanxi Fu1, Jichuan Shen2, Long Lu3, Yajing Li4, Yimin Cao2, Ming Wang2, Sen Pei5, Zhicong Yang2, Qing Guo6, Jeffrey Shaman5. 1. Zhejiang Chinese Medical University, Hangzhou, China; Guangzhou Center for Disease Control and Prevention, Guangzhou, China. Electronic address: fuchuanxi@gmail.com. 2. Guangzhou Center for Disease Control and Prevention, Guangzhou, China. 3. Liwan District Maternal and Child Health Hospital, Guangzhou, China. 4. Sinovac Biotech Co., Ltd, Beijing, China. 5. Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA. 6. Zhejiang Chinese Medical University, Hangzhou, China. Electronic address: louisguoqing@126.com.
Abstract
BACKGROUND: Due to waning levels of maternal antibodies (measles; enterovirus 71, EV71; and coxsackievirus A16, CoxA16), some infants may lose protection against infection prior to vaccination. Using a longitudinal design, we examine how maternal antibody levels evolve over time in infants prior to vaccination. METHODS: In 2013-2014, we collected sera at ages 0, 3 and 6months from infants. We assayed for levels of measles IgG antibody (717, 233 and 75 sample sera tested at months 0, 3 and 6, respectively), and neutralizing antibodies for EV71 and CoxA16 (225, 217, and 72). Demographic and health information were collected, and a linear mixed model (LMM) was used to describe antibody levels over time. RESULTS: Pre-vaccination monotonic antibody decreases were observed for measles (1410, 195 and 22mIU/ml, p<0.001), EV71 (1:19.9, 6.3 and 4.5, p<0.001) and CoxA16 (1:16.3, 5.9, and 4.5, p<0.001). At 6months of age, only 2.7% (95%CI, 0.6-8.3), 6.8% (95%CI, 2.7-14.4) and 5.6% (95%CI, 1.9-12.7) of infants were antibody positive for measles, EV71 and CoxA16, respectively. LMM findings indicated that infants with higher antibody titers at birth experienced a greater loss of antibody level. An infection rate of 1.3% (95%CI, 0.1-6.1) was reported for both EV71 and CoxA16. CONCLUSIONS: Further modifications of vaccination strategies for measles, earlier vaccination for EV71 infection, and deployment of a CoxA16 vaccine need to be considered to limit infection among the very young.
BACKGROUND: Due to waning levels of maternal antibodies (measles; enterovirus 71, EV71; and coxsackievirus A16, CoxA16), some infants may lose protection against infection prior to vaccination. Using a longitudinal design, we examine how maternal antibody levels evolve over time in infants prior to vaccination. METHODS: In 2013-2014, we collected sera at ages 0, 3 and 6months from infants. We assayed for levels of measles IgG antibody (717, 233 and 75 sample sera tested at months 0, 3 and 6, respectively), and neutralizing antibodies for EV71 and CoxA16 (225, 217, and 72). Demographic and health information were collected, and a linear mixed model (LMM) was used to describe antibody levels over time. RESULTS: Pre-vaccination monotonic antibody decreases were observed for measles (1410, 195 and 22mIU/ml, p<0.001), EV71 (1:19.9, 6.3 and 4.5, p<0.001) and CoxA16 (1:16.3, 5.9, and 4.5, p<0.001). At 6months of age, only 2.7% (95%CI, 0.6-8.3), 6.8% (95%CI, 2.7-14.4) and 5.6% (95%CI, 1.9-12.7) of infants were antibody positive for measles, EV71 and CoxA16, respectively. LMM findings indicated that infants with higher antibody titers at birth experienced a greater loss of antibody level. An infection rate of 1.3% (95%CI, 0.1-6.1) was reported for both EV71 and CoxA16. CONCLUSIONS: Further modifications of vaccination strategies for measles, earlier vaccination for EV71 infection, and deployment of a CoxA16 vaccine need to be considered to limit infection among the very young.