Seroepidemiology Of EV71 And CA16 Infections And Willingness Of Parents To Vaccinate Their 6-60 Months Children With EV71 Vaccines In Jiangsu And Guangdong Provinces

Background As one of the most common contagious diseases in children under five years old,hand-foot-mouth disease(HFMD)is primarily caused by Enterovirus 71(EV71)and coxsackieviruses A16(CA16).Since 2015,three inactivated EV71 vaccines have been approved in China.The vaccination coverage of EV71 vaccine has been relatively low.Methods The purpose of this study was to investigate the willingness and influencing factors of EV71 and ca16 neutralizing antibody levels in children in Jiangsu and Guangdong province and their parents to vaccinate their children against EV71-induced HFMD after EV71 vaccines was approved,thus providing information for the prevention and control of HFMD and for improving the coverage of EV71 vaccine.From July 19,2018 to August22,2018,cross-sectional surveys were conducted on children and their parents in 3 counties in Jiangsu province(Sheyang County,Ganyu County and Xinyi County)and 2 counties in Guangdong province(Gaozhou County and Yangchun County).Children’s blood was collected by trained investigators,and parents of school-age children were asked face-to-face to fill out the questionnaire to evaluate parental understanding and attitude towards HFMD and EV71 vaccine.we used the rank sum test and chi-square test to analyze the difference in the geometric mean titers(GMT)and serum positive rates of neutralizing antibodies among children of different sex and age.we used univariate and multivariate binary logistic regression analyses to explore potential influencing factors that influence parental willingness to vaccinate their age-appropriate children against EV71-induced HFMD.Results A total of 2675 children participated in the serological survey.children in EV71 and CA16 at different ages and the antibody titer distribution was basically the same.The EV71 neutralizing antibody positive rate of infants aged 2 to 6 months decreased(70.93%-29.17%),that of infants aged 7 to 11 months remained at a lower level(7.50%-28.57%),and that of infants aged 1 to 6 years increased with age(30.45%-61.67%).The positive rate of CA16 neutralizing antibody in children aged 2 to 6 months decreased gradually(60.47%-16.67%),in infants aged 7 to 11 months was lower(7.50%-19.35%),the positive rate of CA16 neutralizing antibody in children aged 1 to 6 years increased rapidly with age(7.18%-63.89%).The seroprevalence rates of neutralizing antibodies against both EV71 and Cox A16 declined gradually in infants aged from 2 to 6 months old(from 6.98%to 0%),and were relatively low in children aged 7 months to 2 years old(0-0.61%).Nonetheless,it increased in children aged 3 to 6 years old,but reached a peak value(4.79%)in infants at the age of 5 years.The positive probability of EV71 and CA16 neutralizing antibody in children aged 2 to3 months was between 0-6.98%.Of the 1766 parents who participated,87.94% were willing to vaccinate their children with EV71 vaccines.Parents who either: lived in Ganyu [Adjusted odds ratio(a OR)=0.45,95% confidence interval(CI):0.28-0.74] or Xinyi County(a OR =0.27,95%CI:0.16-0.44),had a university or higher degree(a OR=0.43,95%CI:0.20-0.91),had good knowledge of EV71 vaccines(a OR=0.77,95%CI:0.66-0.91),perceived their children’s disease susceptibility(a OR=0.67,95%CI:0.47-0.97),worried about the severity of HFMD(a OR=0.44,95%CI:0.32-0.60)and could afford the EV71vaccines(a OR=0.44,95%CI:0.32-0.60)had a higher willingness to vaccinate their children.Conclusion The presence of EV71 and CA16 co-infection in our study.Therefore,It is necessary to pay attention to the change of virus serotype and develop a universal vaccine or multivalent vaccine for HFMD.Most parents were willing to vaccinate their children against EV71-related HFMD.Parental location,education level,knowledge of EV71 vaccine,concern about susceptibility and severity of HFMD,concern about price of EV71 vaccine were all factors that influenced willingness to vaccinate.