RÉSUMÉ
This study evaluated the scientific nature and effectiveness of iterative optimization of prevention and control measures for local outbreaks caused by the BA.2 and BA.5.2 COVID-19 strains in Fujian Province in 2022,to provide a scientif-ic basis for responding to future new or recurrent respiratory infectious diseases.According to the theory of infectious disease dynamics,relevant information regarding the local epidemic situation caused by the BA.2 sub-type Omicron virus strain in March 2022 and BA.5.2 sub-type Omicron virus strain in October 2022 in Fujian Province was collected.The susceptible exposed infectious removed(SEIAR)model of COVID-19 infection with a latent period and asymptomatic infected persons was used to analyze the transmission dynam-ics of two local epidemic situations,and evaluate the preven-tion and control effects.The incubation period of the BA.2 epidemic was 3 days(1～9 days),the intergenerational inter-val was 3 days(1～5 days),and the initial Rt was 3.0(95％CI:2.7～3.3).The incubation period of the BA.5.2 epidemic was 2 days(1～6 days),the intergenerational interval was 1 day(0～2 days),and the initial R,was 1.9(95％CI:1.7～2.1).The fittingresults for the BA.2 and BA.5.2 epidemics were good,and no statistical difference was observed between the predic-ted and actual numbers of cases(x2BA.2=31.53,x2BA.5.2=27.88,P＞0.05).If an emergency response had not been initiated,the BA.2 epidemic would have continued to spread andpeak on April 7th,with an estimated 638 035 cases.The BA.5.2 epidemic would have rapidly spread,reaching a peak on November 14th,with an estimated 685 940 cases.If one incubation period were detected early,the scale of the BA.2 epidemic would have decreased by 25.73％;if two incubation periods were detected early,the scale would have decreased by 79.56％,and if one incubation period had been delayed,the scale would have expanded by 13.72％.If one incubation period had been detected early in the BA.5.2 epidemic,the scale would have decreased by 35.04％;if two incubation periods had been detected early,the scale would have decreased by 92.47％;and if one incubation period had been delayed,the scale would have increased by 19.75％.The guiding ideology,and the prevention and control measures for handling two local epidemics were optimized and iterated.Our study indicated that implementing the"four early"measures ef-fectively decreased the scale of the epidemic,and earlier detection was associated with more significant control effects.This study provides valuable information for the prevention and control of new or recurrent respiratory infectious diseases.