Measles immunity in the China-Myanmar border region, Lincang city, Yunnan province, 2017

Background: A recent measles importation-related outbreak in the China-Myanmar border region required outbreak response immunization to stop the outbreak, raising the question of measles immunity in the area. We conducted two measles serological surveys to develop a seroepidemiological profile of native Chinese citizens and registered Myanmar immigrants to identify strategies to promote measles elimination in the border region. Methods: We conducted a clinic-based measles serosurvey of Myanmar registered immigrants (n = 300) and a population-based serosurvey of Chinese Lincang residents (n = 355). Serum samples were tested with enzyme-linked immunosorbent assays to assess immunity to measles. Results: We found that Myanmar immigrants had a seropositivity rate of 85.3% (95% CI: 81.3-89.4) with a GMT of 924.9 mIU/ml, and Lincang Chinese nationals had a seropositivity rate of 94.6% (95% CI:92.3-97.0) with a GMT of 1363.3 mIU/ml. Myanmar children 2-6 years of age and 7-14 years of age were more likely to be susceptible to measles than same-aged Chinese children: odds ratios 23.00 (95% CI: 5.10-103.69, P < .001) and 7.95 (95% CI: 1.66-38.01,P = .009), respectively. Conclusions: We recommend conducting a catch-up vaccination program for Myanmar children <= 15 years old.