[Analysis of indexes used to evaluate immunization coverage rate of first dose of measles containing vaccine].

Objective: To obtain an objective index of evaluating the immunization coverage rate of first dose of measles containing vaccine (MCV1)by comparison of the indexes in Guizhou Province.

Methods: Multistage random sampling method was applied to draw subjects from healthy children who had no measles history and aged from 8 months to 6 years of age. The investigated immunization coverage rate (IIR) and the estimated immunization coverage rate (EIR) were evaluated according to the positive rate of measles antibody as a gold standard, and the data of incidence cases as a reference.

Results: The IIR was 86.0% for the group aged from 8 months to 1 year, 90.1% for the group aged from 2 to 3 years and 90.2% for the group aged from 4 to 6 years. The adjusted estimated immunization coverage rate (AIIR) was 89.8%, 94.8% and 95.3%, respectively. Given the vaccine efficacy (VE) was 82.9%, the EIR1 was 59.8%, 71.6% and 77.9%, respectively and the AEIR1 was 68.2%, 79.7% and 86.8%, respectively; given the VE was 95%, the EIR1 was 84.3%, 90.1% and 92.7%, respectively, and the AEIR1 was 88.6%, 93.4% and 96.0%, respectively. The EIR2 was 97.9%, 94.5% and 91.4%, respectively. The relative difference was from 0 to 2.4% when compared with the estimated positive rate of AIIR and AEIR1 given the VE was 95% with the actual positive rate of measles antibody, the difference had no statistical significance(P>0.05). The relative error was low for the estimate positive rates of AIIR and EIR2 and AEIR1 (given the VE was 95%) for the children that had not suffered from measles, the relative error varied from 7.0% to 15.8%.

Conclusion: The investigated immunization coverage rate after adjustment and the AEIR1 (VE 95%) were in line with the actual positive rate of measles antibody, which suggests that we should set an integral evaluation system for the immunization coverage rate based on AIIR and AEIR1.