Study On Prevention And Control Of Novel Corona Virus Delta Mutant

ObjectiveTo analyze the transmission dynamics of novel corona virus Delta mutation in Guangzhou and xi ’an,and comprehensively evaluate the impact of the difference in prevention and control strategies between Guangzhou and xi ’an on the spread of COVID-19,providing a scientific basis for China’s future response to COVID-19 outbreaks caused by novel corona virus Delta mutation.MethodsThis research adopts the Guangzhou health committee and the committee of Xi ’an health public release of epidemic prevention and control of data and information,using the Excel software collect epidemic data and establish the database,based on constructing COVID SEIR model-19 transmission dynamics model,probe into Guangzhou and Xi ’an COVID-19 the spread of the epidemic dynamics,two city simulation under different control strategies The prevention and control effect of the epidemic.Results1.Delta mutant outbreak status.From April 10,2020 to May 13,2021 before the outbreak of Delta variant,there were 14 clusters of outbreaks with a cumulative number of more than 30 cases in China,with an average of one outbreak occurring every 27 days.The total number of cases was 5194,with an average of 13.85 cases per day,and the average number of infections per outbreak was 371 From May 21,2021 to January 20,2022,12 clusters of outbreaks with cumulative cases of more than 30 cases were caused by Delta variant strain in China,with an average of one outbreak occurring every 16.8 days.The total number of cases was 6978,with an average of 34.54 cases per day and an average of581.5 cases per epidemic.2.The first case in Guangzhou was confirmed on May 21,2021,and the last case was confirmed on June 18,2021.The total number of cases was 153,lasting 29 days The first case in Xi ’an was confirmed on December 9,2021,and the last case was confirmed on January 20,2022,with a total of 2,053 cases in 43 days3.Model fitting and sensitivity analysis.Guangzhou’s vaccination rate at the time of the outbreak was 63.4 percent,while Xi ’an was 95 percent.According to the differences of epidemic prevention and control strategies between the two cities,parameters such as vaccine efficacy and effective infectious period were adjusted.Finally,the SEIR model fitting accuracy of Guangzhou and Xi ’an was good,with Mean Absolute Percentage Error MAPE of 10.28% and 12.4%,respectively.Sensitivity analysis showed that when the effective transmission period was reduced to one day,the cumulative number of cases in Guangzhou and Xi ’an would be reduced by 56% and 84%,respectively.When the infection rate is reduced by 50%,the number of cases in the two cities will be reduced by 64% and80% respectively.When the vaccine protection rate is increased to 90 percent,the number of cases in the two cities will be reduced by 47 percent and 90 percent respectively.4.And the effectiveness of prevention and control strategies.If the prevention and control measures are fully relaxed,the cumulative number of cases in Guangzhou and Xi’an will reach 1,726 and 5,426 respectively,12.8 times and 2.77 times higher than the baseline.If only one of the effective transmission periods,transmission rates and vaccination rates is controlled,the comparison of the three control strategies shows that controlling the transmission rate minimizes the cumulative number of cases.If two of them are controlled with strict intensity of prevention and control,the cumulative number of cases in the two cities can be reduced by 78%(Guangzhou)and 95%(Xi ’an)by strictly limiting the limited infectious period and infection rate of the epidemic.The combination of strictly limiting the duration of infection and increasing vaccination coverage reduced the cumulative number of cases by 56%(Guangzhou)and 93%(Xi ’an)in the two cities.The combination of strict limits on infection rates and increased vaccination coverage reduced the cumulative number of cases in the two cities by 80%(Guangzhou)and 96%(Xi ’an).With strict management of effective transmission period,transmission rate and vaccination rate,the cumulative number of cases can be reduced by up to 85%(Guangzhou)and 98%(Xi ’an)compared to baseline.Conclusions1.Both the scale and frequency of Delta variant outbreaks are higher than previous outbreaks.This is related to the Delta variant greatly increasing the transmissibility of the virus and reducing the protective efficacy of the vaccine.2.Both Guangzhou and Xi ’an were caused by the Delta virus strain,but Guangzhou was significantly better than Xi ’an in terms of emergency response time,case tracking efficiency,nucleic acid detection frequency and other epidemic prevention measures.Thus,the cumulative number of cases in Guangzhou is much lower than that in Xi ’an.3.The combination of shortening the effective transmission period of the infected person,reducing the transmission rate of the virus and improving the protective efficacy of the vaccine can effectively control the spread of the Delta virus strain and achieve the early prevention and control of the epidemic.