[Analysis on coverage rate of primary immunization of measles vaccine among migrant children in Yiwu, Zhejiang province from 2007 to 2010].

OBJECTIVE: To investigate the coverage rate of primary immunization of measles containing vaccine (MCV1) among migrant children in Yiwu,Zhejiang province. METHODS: Household cluster sampling survey and probability proportion to size sampling method were adopted. A total of 967 migrant children born from 1st July 2007 to 1st July 2010 and their caregivers were selected as target population. Standard face-to-face interviews were conducted to investigate the subjects' knowledge, attitude, practice (KAP) of immunization, MCV1 vaccination and determinants. Multi-variable weighted average score method was adopted to evaluate the result of our survey on KAP. Kaplan-Meier analysis was adopted to assess the coverage of MCV1 and Cox regression analysis was adopted to explore the influencing factors associated with the coverage of MCV1. RESULTS: Out of the 967 children, 104 were born in 2007, accounting for 10.8%; 301 were born in 2008, accounting for 31.1%; 343 were born in 2009, accounting for 35.5% and 219 were born in 2010, accounting for 22.6%. Among the surveyed caregivers, 71.9% (695/967) were mothers and 90.2% (872/976) were migrant from other provinces. According to the result of survey on KAP among caregivers, 56.2% (543/967) scored ≥ 4 points on knowledge, 75.8% (734/967) scored ≥ 4 points on attitude and 48.7% (471/967) scored ≥ 4 points on behavior. 86.6% (838/967) of surveyed caregivers' education levels were under junior middle school.85.9% (831/967) of the migrant children were born in hospitals.36.3% (351/967) of the surveyed families' household income were under 2000 yuan per month.32.7% (316/967) of surveyed caregivers waited less than 15 min for immunization for each time. Coverage rate of MCV1 was 85.9% (831/967; 95%CI: 83.7%-88.1%). The timely coverage rates at 8 months, 12 months, and 24 months were 58.8% (569/967; 95%CI: 55.5%-62.1%), 88.2% (853/967; 95%CI: 86.0%-90.4%) and 98.6% (953/967; 95%CI: 97.8%-99.4%), respectively. The average age of MCV1 immunization for each birth cohort between 2007 and 2010 were 10.4, 10.1, 10.1 and 9.3 month, respectively; without statistical significance (χ(2) = 0.722, P = 0.398). According to the analysis by Cox regression, the caregivers aged ≤ 25 years (24.3% (235/967), RR = 1.520 (95%CI: 1.280-1.800)), the caregivers' education level above college (2.8% (27/967), RR = 3.841 (95%CI: 2.287-6.451)), delivered in county-level hospital (49.4% (478/967), RR = 6.048 (95%CI: 4.311-8.485)), household income > 4000 yuan per month (21.7% (210/967), RR = 1.366 (95%CI:1.163-1.604)), the average score of attitude towards immunization ≥ 4 points (75.9%(734/967), RR = 2.613 (95%CI: 1.026-6.655)), the average waiting time for each vaccination ≤ 15 min (32.7% (316/967), RR = 2.116 (95%CI: 1.341-3.339)) were the important factors to improve the timely immunization coverage rate of MCV1 among migrant children. CONCLUSION: The coverage of MCV1 were obviously delayed among migrant children in Yiwu, Zhejiang province. We suggest that the investigation of migrant children should be strengthened and remind or recall mechanism for immunization should be established. Increasing the open days for immunization clinics and reducing the waiting time for vaccination could also improve the coverage and timeliness of the MCV vaccination.