Study on Dynamic Changes of the Maternal Anti-EV71 and Anti-CVA16 Antibody Levels in Infants and Young Children

Hand, Foot and Mouth Disease（HFMD）is an infectious disease in infants and young children caused by enterovirus. There was a great outbreak of HFMD in China, 2008, which brought not only panic to the people, but also huge economic loss. Since 2008, HFMD has become one of the category c infectious diseases in China. Studies showed that Human Enterovirus 71 (EV71) and coxsackievirus A 16 (CVA16) are the most common reasons for this disease. And the investigators are going to develop the vaccines for this disease. There is an urgent need to know the dynamic changes of the maternal anti-EV71 and ant-CVA16 level in infants and young children. In April 2007, the investigators started a clinical trial named 'The Safety and Immunogenicity of Recombinant Hepatitis B Vaccines in the Health Neonates' (ClinicalTrials.gov ID: NCT01183611). In that study the investigators already built a cohort of Health Neonates, followed them and obtained the blood serum on the day 0, 30, 210 and 360 after born. So, based on the cohort and blood serum the investigators got, the investigators plan this study to retrospectively investigate their HFMD histories from birth and follow-up for another year to get the information about the incidence of HFMD. The investigators also plan to assay the maternal anti-EV71 and anti-CVA16 antibodies on the day0 and the dynamic changes of antibodies on 1st month, 7th month (day 210), 1st year (day 360) and on October, 2010.