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[Dynamic maternal measles antibody level in infants: a longitudinal study].

OBJECTIVE
To understand the dynamic maternal measles antibody level in infants in Guangzhou.


METHOD
Women who delivered babies in a maternal and child health care hospital in Guangzhou and their infants who were never affected by measles were included in our study. All the serum samples collected from mothers and infants were tested by using enzyme linked immunosorbent assay(ELISA)for the quantitative measurement of measles IgG antibodies. A longitudinal sero-epidemiological study was conducted to investigate the duration of the presence of measles maternal antibodies in infants based on the measurement at different time points(0, 3, 5, 7 month).


RESULT
A total of 689 mothers and their 691 infants(two pairs of twins)were included in the study. The concentration and the sero-positivity rate of measles antibody in mothers was 513.8 mIU/ml and 81.6% respectively. The concentration and the sero-positivity rate of measles antibody in infants was 732.8 mIU/ml and 87.3%, respectively. The measles antibody levels of newborns were positively associated with those of mothers(r=0.917 5, P<0.001), which declined rapidly at 3 months after birth and mostly turned to be negative at 7 months after birth. Measles antibody turned be negative at 3 months after birth in low, middle level groups, but remained to be positive in high level group at 5 months after birth.


CONCLUSION
The maternal measles antibody could rarely protect infants at age of 8 months even though mother had been vaccinated or acquired natural immunity. It is suggested to adjust the time of the first dose measles vaccination in infants and increase the measles antibody level of child bearing aged women to reduce the incidence of measles in infants.