IgG antibody level to measles in healthy population in Hangzhou, Zhejiang, 2016−2020

  Objective  To evaluate the IgG antibody level to measles in healthy population in Hangzhou, Zhejiang province, during 2016−2020.

  Methods  Stratified random sampling was conducted to select 11 age groups in healthy population in Hangzhou. Enzyme linked immune sorbent assay (ELISA) was used to detect serum measles IgG antibody, and the positive rate of antibody and geometric mean concentration (GMC) were analyzed.

  Results  The positive rate of measles IgG antibody was 89.48% (1488/1663) and measles IgG GMC was 851.94 mIU/mL in healthy population in Hangzhou. The positive rate of measles IgG antibody in all age groups ranged from 58.28% (<1 year old group) to 98.01% (3− year old group) (χ²=198.70, P<0.01), the GMC was between 573.44 mIU/mL (<1 year old group) and 1682.98 mIU/mL (1- year old group) (F=23.12, P<0.01). The positivity rates and the GMCs in subjects who received 0, 1, ≥2 and unknown doses of measles containing vaccine (MCV) were 55.26%, 89.19%, 93.32%, 91.00% (χ²=155.21, P<0.001) and 418.20 mIU/mL, 1536.88 mIU/mL, 966.59 mIU/mL, 735.17 mIU/mL (F=21.68, P<0.001), respectively. The positive rate of measles IgG antibody and the GMC decreased from 91.59%, 1644.70 mIU/mL (＜1 year after immunization) to 87.65%, 649.03 mIU/mL (≥10 years after immunization) in people with history of MCV.

  Conclusion  The overall measles IgG antibody level in healthy population in Hangzhou was high, the population immunization level was associated with area, age and immunization history and decreased over time after MCV immunization. It is necessary to make some discussion about the measles immunization strategy in adults.