Survey of antibody level to varicella-zoster virus in healthy population aged 3-18 years in Futian district, Shenzhen

Objective To understand the varicella antibody level in students aged 3-18 years old in Futian district, discuss the possibility of supplementing 1 dose of varicellea vaccine in children aged 1-12 years. Methods The blood samples were collected from the children in child care settings, primary schools and middle schools in Futian for the detection of varicella antibody with VZV-IgG antibody kit (ELISA) from 2013 to 2015. Results A total of 3044 students were surveyed, the positive rate of varicella antibody was 62.81%, the geometric mean concentration (GMC) was(668.45187.29)mIU/ml. The lowest positive rate (42.25%) and GMC (155.1766.25 mIU/ml) was in age group 6 years. The lowest positive rate (47.20%) and GMC (227.6185.61 mIU/ml) was in age group 6-8 years after vaccination. The positive rate and GMC in students receiving vaccination was higher than those receiving no vaccination, the difference was significant (2=48.240,P=0.000,t=10.830, P=0.022). The incidence of varicella in Futian ranged from 10.74/lakh to 53.51/lakh during 2006-2014. Up to 72.45% of the cases were aged 3-18 years. A total of 53 varicella outbreaks occurred during 2010-2014, in which 89.36% occurred in grade 1-4 of primary schools. Conclusion After 1 dose varicella vaccination, the positive rate and concentration of antibodies decreased firstly, which was lowest at 6 year, then increased gradually. It is recommended to give 2 doses varicella vaccination for children aged 1-12 years on the bases of ensuring the safety of the second dose vaccination.