Were infections in migrants associated with the resurgence of measles epidemic during 2013-2014 in southern China? A retrospective data analysis

Abstract

Objective: The 2009 province-wide and 2010 nationwide supplementary immunization activities (SIAs) greatly reduced measles prevalence in Guangdong, a province in southern China with the largest migrant population. However, during 2013-2014, Guangdong experienced a resurgence of the measles epidemic. This study was performed to examine the association between infections in migrants and the resurgence of the measles epidemic.

Methods: The records of 22 362 clinically and laboratory-confirmed measles cases from the years 2009 to 2014 were extracted from the National Infectious Disease Monitoring Information System. The epidemiological characteristics of infections in migrants during 2009-2012 were compared to those during 2013-2014.

Results: Infections in migrants were not significantly associated with the resurgence of the measles epidemic in 2013-2014 (p=0.98). Nevertheless, for infections among locals and migrants during 2009-2012 and 2013-2014, substantial increases in the proportion of infection were detected among children aged <8 months and the unvaccinated population (p<0.01).

Conclusions: The study findings suggest that infections in migrants might not have been the major cause of the epidemic resurgence of measles. Instead, the resurgence was likely due to infections among children aged <8 months and the unvaccinated. Thus, officials are advised to give higher priority to appropriate populations when formulating control measures, and to strengthen routine surveillance of vaccination coverage among them.

Keywords: China; Immunization; Measles; Migrant; Rural; Vaccine.