Objective To determine the antibody levels of varicella-zoster virus （VZV） in healthy individuals aged 1 to 30 years in Songjiang District of Shanghai， and to provide evidence for further development of varicella immunization strategies for healthy population.
Methods Six village committees were selected in Songjiang District through multi-stage stratified random sampling method from July to September 2022. Healthy individuals aged 1 to 30 years old in these villages were recruited and 3‒5 mL of venous blood was collected. Anti-VZV IgG antibody was tested by ELISA. Positive rate of anti-VZV IgG antibody and geometric mean concentration （GMC） were determined.
Results A total of 315 healthy individuals aged （10.97±8.38） years were included in this study， of which 165 were males aged （11.00±8.52） years and 150 were females aged （10.96±8.25） years. Blood samples were collected and tested for anti-VZV IgG antibody， with the overall positive rate of 55.24% （174/315）. The GMC was calculated to be 99.73 mIU·mL-1， with the GMC in those tested positive for anti-VZV IgG antibody of 413.11 mIU·mL-1. The positive rate of anti-VZV IgG antibody and GMCs across age groups ranged between 13.33%‒86.67% and 16.36‒355.14 mIU·mL-1， respectively. The highest GMC was found in the group of 20‒30 years old （355.14 mIU·mL-1）， followed by 132.41 mIU·mL-1 in the group of 5‒ years old and 138.12 mIU·mL-1 in the group of 15‒ years old. Moreover， the positive rate was 38.47% in the group with 1-dose varicella vaccine and 63.49% in the group with 2 doses， while the GMC were 53.28 mIU·mL-1 and 130.79 mIU·mL-1 in these two groups， respectively. Multivariable analysis revealed that occupation was a risk factor associated with anti-VZV IgG antibody （OR=2.540）. Stratified analysis by varicella immunization history showed that among 2-dose vaccination group， time interval since the last dose was a protective factor （OR=0.315）.
Conclusions The overall positive rate of anti-VZV IgG antibody in healthy population in Songjiang District of Shanghai remains low. The 2-dose varicella vaccination should be strengthened to improve the coverage in susceptible population.
DownLoad: