Investigation Of Demographic,Virological Characteristics And Prognosis Of Asymptomatic Patients With COVID-19

Background:COVID-19 is a worldwide pandemic,and asymptomatic transmission is one of the important problems for SARS-CoV-2 community spread,however,little information is available on demographic,virological characteristics and prognosis of asymptomatic patients.Objective:(1)To explore the demographic characteristics of asymptomatic patients with COVID-19,and identify which groups are prone to become asymptomatic patients,then focus on and monitor them to reduce asymptomatic transmission.(2)To explore the pathogenic characteristics of different novel coronavirus variants and screen out the variants that we should focus on.(3)To clarify the prognosis of different patients to guide prevention or treatment.Methods:Authorized by the Health Commission of Guangdong Province and the COVID-19 Prevention and Control Headquarters of Guangdong Province,a retrospective analysis was conducted on 233 patients with confirmed viral variants admitted to 32 designated hospitals for COVID-19 in Guangdong Province from September 1,2020 to February 28,2021 with the help of the telemedicine platform of Guangdong Province.According to the clinical characteristics of patients they were divided into the asymptomatic group and the symptomatic group.Statistical methods including statistical description,normal test,parametric test and non-parametric test were adopted with the help of SPSS26.0 software.Age,sex,comorbidities,countries or regions of origin,variants,important time points in clinical course,infection indexes and organ function indexes of the patients were compared and analyzed.Results:Compared with symptomatic,the asymptomatic were found to be younger(32.71±12.17 vs 36.73±12.55,P=0.019)and have fewer comorbidities(8.4%vs 20.0%P=0.021),lower rate of hypertension(2.4%vs 93%,P=0.083),chronic liver disease(1.2%vs 8.7%,P=0.045),but higher rate of chronic lung disease(4.8%vs 0.7%,P=0.056).233 patients in the study came from 57 different countries and regions.Patients from South Africa,Indonesia,Myanmar,Russia,Ghana were mainly asymptomatic,while the patients from the United Kingdom,the United States,Philippines,Bangladesh,Nigeria,Malaysia,Hong Kong,France and Kuwait were mainly symptomatic.PANGOLIN B was the main part of novel coronavirus in the study,and there were 12 major variants(number of cases n≥5):B(n=10),B.1(n=34),B.1.1(n=26),B.1.1.63(n=9),B.1.1.7(n=6),B.1.351(n=11),B.1.36(n=10),B.1.36.1(n=10),B.1.36.16(n=13),B.1.5(n=10),B.1.524(n=5)and B.6(n=10).By analyzing the pathogenic characteristics of different variants,it was found that patients infected with B.1.1(53.8%),B.1.351(81.8%),B.1.524(60.0%)were mainly asymptomatic.Those infected with B(90.0%)、B.1(61.8%)、B.1.1.63(88.9%)B.1.1.7(83.3%)、B.1.36(60.0%)、B.1.36.1(70.0%)、B.1.36.16(76.9%)、B.1.5(90.0%)、B.6(90.0%)were mainly symptomatic.Compared with the symptomatic,the asymptomatic were found to have higher infection indexes such as WBC(6.155 vs 5 280,P=0.002)and LYMPH%(31.30%vs 27.95%,P=0.011),lower infection indexes such as NE%(55.65%vs 60.40%,P=0.019),PCT(0.055 vs 0.108,P=0.021),and lower organ function indexes such as ALT(21.00 vs 23.53,P=0.029),CK(53.50 vs 71.00,P=0.025)and DDI(0.22 vs 85.00,P<0.001).Time of SARS-CoV-2 nucleic acid turning negative(26 days,P=0.085;41 days,P=0.007)and length of hospital stay(28 days,P=0.085;43 days,P=0.004)in patients infected B.1.351 or B.1.524 was significantly longer than the other variants.Conclusion:(1)In terms of demography and epidemiology,after infected with the novel coronavirus,younger patients with fewer comorbidities(chronic liver disease,hypertension),relatively good organ function and stable immune function are more likely to be asymptomatic.(2)In terms of virology,patients infected with variants B.1.1,B.1.351 and B.1.524 are more likely to be asymptomatic,and the prognosis is worse or complicated after infection with B.1.351 and B.1.524,which deserves more attention.