Epidemiological characteristics of measles in Jinshan District of Shanghai in 2002‒2019

Objective To determine the epidemiological characteristics of measles in Jinshan District of Shanghai in 2002‒2019.

Methods This study was a secondary data analysis using measles surveillance system and epidemiological case reports in Jinshan District from January 2002 through December 2019. Temporal characteristics of the disease onset was determined by a concentration method. ArcGis 10.4 and SaTScan 9.6 software were used for spatiotemporal clustering scanning analysis.

Results From 2002 through 2019， a total of 289 cases of measles were reported in Jinshan District， Shanghai， with an average annual incidence of 2.24 per 10⁵. The annual incidence fluctuated from 0 to 11.27 per 10⁵. The highest incidence was recorded in 2005 （11.27 per 10⁵）， followed by a decline； however， there was a rebound in 2008 （5.26 per 10⁵） and 2015 （3.30 per 10⁵）. The concentration M was determined to be 0.62， showing a clear seasonality concentrated in February to May. The spatiotemporal scan found that spatial and temporal clusters were more likely to occur in the areas with higher population density such as Zhujing Town and Shihua Community and between 2002 and 2009. The majority of measles cases were infants and children under the age of 1 and adults aged 20‒39 years. Approximately 66.78% of measles cases reported unknown vaccination history. In addition， in children aged 8 month to 4 years， the vaccination rate of measles-containing vaccines in the domestic migrants was much lower than the local residents （χ²=4.44， P=0.035）.

Conclusion The incidence of measles in Jinshan District presents a downward trend. The population affected has a "two-way displacement"， which is concentrated in the more populated areas. It is necessary to strengthen measles surveillance and implement supplementary immunization programs with measles-containing vaccines for at-risk populations.