To analyze the effect of different dosage of measles vaccines (0.2 ml or 0.5 ml) to measles antibody level in 8 month-old infants and study the relationship between maternal antibody in infants and the immune response to the vaccine.
196 8 month-old infants and their mothers were selected randomly. The measles IgG-antibody in infants before and after vaccination and in their mothers was detected by ELISA.
Total 101 infants received 0.2 ml MV and 95 infants received 0.5 ml MV. (1) Among all infants who were antibody negative before vaccination, the immune success rate was 88.24% in the Group 1 and 97.3% in Group 2. There were significant differences between the 2 groups (chi2=4.656 P=0.031). (2) Infants who were antibody positive before vaccination the immune success rate was 56.25% in Group 1 and 57.14% in Group 2. There were no significant differences between the 2 groups (chi2=0.003 P=0.957). (3) Before receiving MV, the seronegative rate in total 196 infants was 81.12%, but the seronegative rate in their mothers was 7.65%.
For 8 month-old infants, the maternal antibody has limited influence on the immune success rate. Increasing the dosage to 0.5 ml could increase the success rate and decrease the primary immune failure among infants who were antibody negative pre-vaccination. However, for those infants who were antibody positive pre-vaccination, the antibody level was not increase along with the increasing of the vaccine dosage.