1起由奥密克戎BA.2引起的原因不明新冠肺炎本土聚集性疫情流行病学特征分析

Characteristic analysis of a local clustered outbreak of COVID-19 pneumonia caused by SARS-CoV-2 Omicron BA.2

目的通过分析1起原因不明新型冠状病毒肺炎(简称新冠肺炎)本土聚集性疫情流行病学特征,为下一步制定科学防控措施提供依据。方法通过回顾性调查方法对在2022年3-4月发生在海珠区12例本土聚集性疫情的发生原因、传播方式、疫苗接种效果及防控措施等因素,采用描述流行病学方法进行分析。结果这起疫情共报告12例感染者,均为确诊病例。临床表现:发热10例(占83.33%),咽痛7例(占58.33%),咳嗽7例(占58.33%),乏力5例(占41.67%),头痛或头晕4例(占33.33%),胃肠道症状2例(占16.67%),肌肉酸痛1例(占8.33%)。临床分型:轻症10例(占83.33%),普通型2例(占16.67%),无重症和死亡病例。发病时间最早为3月27日,最后1例为4月15日。发病高峰集中在4月8和10日,共5例(占41.67%)。病例最短潜伏期2 d,最长14 d,平均6.55 d。按聚集性分布,羊羊服装公司7例(占58.33%),广州市三中学校3例(占25.00%),家庭发病2例(占16.67%)。男女性别比为1∶3,发病年龄最小18岁,最大59岁,12例病例均为青壮年,其中21~<60岁为9例(占75.00%),18~<21岁为3例(占25.00%)。职业分布:职员最多,占58.33%,其次家务待业占25.00%,学生占16.67%。通过1∶3+匹配病例对照研究,对58名高风险密切接触者接种疫苗的发病比较,发病与未发病的疫苗接种率差异无统计学意义(χ^(2)=0.861,P>0.05)。用1∶1+匹配病例对照研究,对58名高风险密切接触者性别发病比较,发病的男女性别比与未发病的男女性别比之间的差异无统计学意义(χ^(2)=0.325,P>0.05)。结论这起疫情由奥密克戎BA.2引起,感染来源不明,存在隐匿传播。因此加强个人防护,发挥医疗单位、药房哨点作用和行业监测作用是新冠肺炎常态化防控十分必要的措施。

Objective To analyze the epidemiological characteristics of a local cluster of corona virus disease 2019(COVID-19)pneumonia caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Omicron BA.2,and thus provide scientific evidence for the formulation of scientific prevention and control measures.Method Descriptive epidemiological methods were used to analyze the causes,transmission,vaccination effects and prevention measures of 12 local clustered outbreaks in Haizhu district in March and April 2022 by retrospective investigation.Results A total of 12 infected patients were reported,all of which were confirmed infected with SARS-CoV-2 Omicron BA.2.Clinical manifestations:10 cases had fever(83.33%),7 cases had sore throat(58.33%),7 cases had cough(58.33%),5 cases had fatigue(41.67%),and 4cases had headache or dizziness(33.33%),2 cases had gastrointestinal symptoms(16.67%),and 1 case had muscle soreness(8.33%).The clinical classification is as follows:10 cases of mild disease(83.33%),2 cases of common type(16.67%),no severe disease and no death.The earliest infection time was March 27,and the last case was April 15.The peak incidence was concentrated on April 8 and April 10,with a total of 5 cases(41.67%).The shortest incubation period was 2 days and the longest was 14 days,with an average of 6.55 days.The geographical distribution indicated that 7 cases from Yangyang Clothing Company(58.33%),3 cases from Guangzhou No.3 Middle School(25.00%),and 2 cases of family clusters(16.67%).The sex ratio of all patients was 1∶3.The youngest age was 18 years old and the oldest was 59years old.The 12 cases were young adults;of which,9 cases were 21-<60 years old(accounting for 75.00%),and 3 cases were 18-<21 years old(25.00%).Occupational distribution:employees were accounting for 58.33%,followed by unemployed accounting for 25.00%,and students accounting for 16.67%.A 1∶3+matched case-control analysis in 58 highrisk close contacts was conducted,and found that infection and vaccination were not statistically correlated(χ^(2)=0.861,P>0.05).Similarly,by conducting a 1∶1+matched case-control analysis,we failed to observed a statistically significantly in the effect of sex on infection(χ^(2)=0.325,P>0.05).Conclusions The outbreak was caused by SARS-CoV-2 Omicron BA.2;the source of infection was still unknown,and there was hidden transmission.Therefore,strengthening personal protection and giving full play to the role of medical units and pharmacies as sentinel points and industry monitoring should be necessary for the normalization of COVID-19 pneumonia prevention and control.