Objective To assess the intensity of varicella epidemics in Urumqi City using the moving epidemic method(MEM),to establish the threshold for varicella surveillance in the city,and to provide a scientific basis for graded prevention and control.Methods MEM was used to model the incidence data of varicella surveillance in Urumqi City from the 30th week of each year to the 10th week of the following year from 2010 to 2019.The screening indexes,including sensitivity,specificity,positive predictive value,negative predictive value,Matthews correlation coefficient,and Youden index,were used to evaluate the epidemic situation of varicella in Urumqi City from 2019 to 2020.Results The data quality from 2012 to 2013 and 2018 to 2019 was poor and was excluded.After remodeling using the data of the remaining years,the optimal parameter value was 3.0,and the sensitivity,specificity and Youden index were 0.73,0.98,and 0.71,respectively,with a good model fitting.The thresholds of moderate,high,and extremely high intensity were 100,126,and 140 cases,respectively.The threshold for pre-epidemic varicella was entered in the 36th week of 2019,followed by a rapid rise above the moderate intensity threshold and reaching the high-intensity peak level in the 45th week of 2019.Conclusion The varicella epidemic early warning model established by MEM can calculate the epidemic start time and epidemic intensity of varicella,and predict the time from the epidemic to the peak period,which is more effective in the early warning of varicella.
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