Role and Containment of Asymptomatic Cases in COVID-19 Transmission

doi:10.12114/j.issn.1007-9572.2021.00.416

Abstract

Abstract: COVID-19 has been plaguing global health for nearly a year.During the past year，many governments took arious measures such as closing schools and office-buildings，imposing social distancing to cut off the virus' transmission route.However，in the gradual return to normality，asymptomatic patients will，and already have，pose grave challenges.This paper reviews the proportion of asymptomatic COVID-19 cases in the global population，the role these cases have played in the transmission，and measures to restrict COVID-19 transmission through asymptomatic cases.

Key words: Pneumonia, COVID-19, SARS-CoV-2, Asymptomatic carriers, Control

摘要： 新型冠状病毒肺炎（COVID-19）已在全球流行近一年，对世界人口健康造成巨大打击。许多国家为切断病毒传播途径，采取关闭学校和工作场所、强制公众保持社交距离等措施。在逐步恢复正常的工作和生活秩序过程中，无症状感染者对COVID-19流行的影响无疑是一个重要挑战。本文针对无症状感染者在人群中的比例、无症状感染者在传播中的作用以及限制无症状感染者造成的病毒传播等方面的研究进展进行综述。

关键词: 肺炎, 新型冠状病毒肺炎, 新型冠状病毒, 无症状感染者, 控制

LIU Qiao,LIU Jue,LIU Min. Role and Containment of Asymptomatic Cases in COVID-19 Transmission　[J]. Chinese General Practice, 2021, 24(8): 917-922. DOI: 10.12114/j.issn.1007-9572.2021.00.416.
刘巧,刘珏,刘民. 无症状感染者对COVID-19流行的影响及其防控措施研究[J]. 中国全科医学, 2021, 24(8): 917-922. DOI: 10.12114/j.issn.1007-9572.2021.00.416.

References

［1］WHO.Weekly epidemiological update-22 December 2020［EB/OL］．（2020-12-22）［2020-12-23］．https：//www.who.int/docs/default-source/coronaviruse/situation-reports/20201222_weekly_epi_update_19.pdf?sfvrsn=9ba3df9a_5&download=true.
［2］ROSER M，RITCHIE H，ORTIZ-OSPINA E，et al．Coronavirus Pandemic （COVID-19）［EB/OL］．［2020-12-23］．https：//ourworldindata.org/coronavirus.
［3］GANDHI M，YOKOE D S，HAVLIR D V.Asymptomatic transmission，the Achilles' heel of current strategies to control COVID-19［J］．N Engl J Med，2020，382（22）：2158-2160．DOI：10.1056/NEJMe2009758.
［4］国务院应对新型冠状病毒肺炎疫情联防联控机制综合组.新型冠状病毒肺炎防控方案（第七版）［EB/OL］．（2020-09-11）［2020-12-23］．http：//www.nhc.gov.cn/jkj/s3577/202009/318683cbfaee4191aee29cd774b19d8d/files/f9ea38ce2c2d4352bf61ab0feada439f.pdf.
［5］WHO.Coronavirus disease （COVID-19）：How is it transmitted?［EB/OL］．（2020-07-09）［2020-12-23］．https：//www.who.int/news-room/q-a-detail/coronavirus-disease-covid-19-how-is-it-transmitted.
［6］OOI E E，LOW J G.Asymptomatic SARS-CoV-2 infection［J］．Lancet Infect Dis，2020，20（9）：996-998．DOI：10.1016/s1473-3099（20）30460-6.
［7］MIZUMOTO K，KAGAYA K，ZAREBSKI A，et al．Estimating the asymptomatic proportion of coronavirus disease 2019 （COVID-19） cases on board the Diamond Princess cruise ship，Yokohama，Japan，2020［J］．Eur Commun Dis Bull，2020，25（10）：2000180．DOI：10.2807/1560-7917.ES.2020.25.10.2000180.
［8］HOXHA A，WYNDHAM-THOMAS C，KLAMER S，et al．Asymptomatic SARS-CoV-2 infection in Belgian long-term care facilities［J］．Lancet Infect Dis，2020：S1473-S3099（20）30560-0．DOI：10.1016/S1473-3099（20）30560-0.
［9］BI Q F，WU Y S，MEI S J，et al．Epidemiology and transmission of COVID-19 in 391 cases and 1286 of their close contacts in Shenzhen，China：a retrospective cohort study［J］．Lancet Infect Dis，2020，20（8）：911-919．DOI：10.1016/S1473-3099（20）30287-5.
［10］SUTTON D，FUCHS K，D'ALTON M，et al．Universal screening for SARS-CoV-2 in women admitted for delivery［J］．N Engl J Med，2020，382（22）：2163-2164．DOI：10.1056/NEJMc2009316.
［11］WU Z Y，MCGOOGAN J M.Characteristics of and important lessons from the coronavirus disease 2019 （COVID-19） outbreak in China：summary of a report of 72?314 cases from the Chinese center for disease control and prevention［J］．JAMA，2020，323（13）：1239-1242．DOI：10.1001/jama.2020.2648.
［12］MEYEROWITZ E A，RICHTERMAN A，BOGOCH I I，et al．Towards an accurate and systematic characterisation of persistently asymptomatic infection with SARS-CoV-2［J］．Lancet Infect Dis，2020：S1473-S3099（20）30837-9．DOI：10.1016/S1473-3099（20）30837-9.
［13］RAHIMI F，TALEBI BEZMIN ABADI A.Challenges of managing the asymptomatic carriers of SARS-CoV-2［J］．Travel Med Infect Dis，2020，37：101677．DOI：10.1016/j.tmaid.2020.101677.
［14］ZOU L R，RUAN F，HUANG M X，et al．SARS-CoV-2 viral load in upper respiratory specimens of infected patients［J］．N Engl J Med，2020，382（12）：1177-1179．DOI：10.1056/NEJMc2001737.
［15］ROTHE C，SCHUNK M，SOTHMANN P，et al．Transmission of 2019-nCoV infection from an asymptomatic contact in Germany［J］．N Engl J Med，2020，382（10）：970-971．DOI：10.1056/NEJMc2001468.
［16］SAYAMPANATHAN A A，HENG C S，PIN P H，et al．Infectivity of asymptomatic versus symptomatic COVID-19［J］．Lancet，2020：S0140-S6736（20）32651-9．DOI：10.1016/S0140-6736（20）32651-9.
［17］ORAN D P，TOPOL E J.Prevalence of asymptomatic SARS-CoV-2 infection：a narrative review［J］．Ann Intern Med，2020，173（5）：362-367．DOI：10.7326/M20-3012.
［18］NISHIURA H，KOBAYASHI T，MIYAMA T，et al．Estimation of the asymptomatic ratio of novel coronavirus infections （COVID-19）［J］．Int J Infect Dis，2020，94：154-155．DOI：10.1016/j.ijid.2020.03.020.
［19］AL-QAHTANI M，ALALI S，ABDULRAHMAN A，et al．The prevalence of asymptomatic and symptomatic COVID-19 in a cohort of quarantined subjects［J］．Int J Infect Dis，2020，102：285-288．DOI：10.1016/j.ijid.2020.10.091.
［20］BAI Y，YAO L S，WEI T，et al．Presumed asymptomatic carrier transmission of COVID-19［J］．JAMA，2020，323（14）：1406-1407．DOI：10.1001/jama.2020.2565.
［21］WONG J，JAMALUDIN S A，ALIKHAN M F，et al．Asymptomatic transmission of SARS-CoV-2 and implications for mass gatherings［J］．Influenza Other Respir Viruses，2020，14（5）：596-598．DOI：10.1111/irv.12767.
［22］PAN X F，CHEN D X，XIA Y，et al．Asymptomatic cases in a family cluster with SARS-CoV-2 infection［J］．Lancet Infect Dis，2020，20（4）：410-411．DOI：10.1016/S1473-3099（20）30114-6.
［23］国务院应对新型冠状病毒肺炎疫情联防联控机制综合组.新冠病毒无症状感染者管理规范［EB/OL］．（2020-04-06）［2020-12-23］．http：//www.nhc.gov.cn/jkj/s7916/202004/9d3edaaebb9a4c369f42c61039be35fe.shtml.
［24］GUAN W J，NI Z Y，HU Y，et al．Clinical Characteristics of Coronavirus Disease 2019 in China ［J］．N Engl J Med，2020 Apr 30；382（18）：1708-1720．DOI：10.1056/NEJMoa2002032.
［25］BURKE R M，KILLERBY M E，NEWTON S，et al．Symptom profiles of a convenience sample of patients with COVID-19 - United States，January-April 2020［J］．MMWR Morb Mortal Wkly Rep，2020，69（28）：904-908．DOI：10.15585/mmwr.mm6928a2.
［26］PAN L，MU M，YANG P C，et al．Clinical characteristics of COVID-19 patients with digestive symptoms in Hubei，China：a descriptive，cross-sectional，multicenter study［J］．Am J Gastroenterol，2020，115（5）：766-773．DOI：10.14309/ajg.0000000000000620.
［27］European Centre for Disease Prevention and Control.Case definition for coronavirus disease 2019 （COVID-19）［EB/OL］．（2020-12-03）［2020-12-23］．https：//www.ecdc.europa.eu/en/covid-19/surveillance/case-definition.
［28］WHO.WHO COVID-19 Case definition［EB/OL］．（2020-08-07）［2020-12-23］．https：//www.who.int/publications/i/item/WHO-2019-nCoV-Surveillance_Case_Definition-2020.1.
［29］Centers of Disease Control and Prevention.Coronavirus Disease 2019 （COVID-19）［EB/OL］．（2020-08-05）［2020-12-23］．https：//wwwn.cdc.gov/nndss/conditions/coronavirus-disease-2019-covid-19/case-definition/2020/08/05/.
［30］Ministry of Health and Ministry of Long-Term Care.Case Definition - Coronavirus Disease （COVID-19）［EB/OL］．（2020-12-01）［2020-12-23］．http：//www.health.gov.on.ca/en/pro/programs/publichealth/coronavirus/docs/2019_case_definition.pdf.
［31］YI Y，LAGNITON P N P，YE S，et al．COVID-19：what has been learned and to be learned about the novel coronavirus disease［J］．Int J Biol Sci，2020，16（10）：1753-1766．DOI：10.7150/ijbs.45134.
［32］Centers of Disease Control and Prevention.Pandemic Planning Scenarios ［EB/OL］．（2020-06-23）［2020-12-23］．https：//www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scenarios.html.
［33］NG Y，LI Z B，CHUA Y X，et al．Evaluation of the effectiveness of surveillance and containment measures for the first 100 patients with COVID-19 in Singapore - January 2-February 29，2020［J］．MMWR Morb Mortal Wkly Rep，2020，69（11）：307-311．DOI：10.15585/mmwr.mm6911e1.
［34］Emerging COVID-19 success story：South Korea learned the lessons of MERS ［EB/OL］．（2020-6-30）［2020-12-23］．https：//ourworldindata.org/covid-exemplar-south-korea.
［35］SKITTRALL J P，FORTUNE M D，JALAL H，et al．Diagnostic tool or screening programme? Asymptomatic testing for SARS-CoV-2 needs clear goals and protocols［J］．Lancet Reg Heal - Eur，2020：100002．DOI：10.1016/j.lanepe.2020.100002.
［36］HUNG I F，CHENG V C，LI X，et al．SARS-CoV-2 shedding and seroconversion among passengers quarantined after disembarking a cruise ship：a case series［J］．Lancet Infect Dis，2020，20（9）：1051-1060．DOI：10.1016/S1473-3099（20）30364-9.
［37］TEHERáN A A，CAMERO RAMOS G，PRADO DE LA GUARDIA R，et al．Epidemiological characterisation of asymptomatic carriers of COVID-19 in Colombia：a cross-sectional study［J］．BMJ Open，2020，10（12）：e042122．DOI：10.1136/bmjopen-2020-042122.
［38］ZHOU F L，LI J F，LU M X，et al．Tracing asymptomatic SARS-CoV-2 carriers among 3674 hospital staff：a cross-sectional survey［J］．EClinicalMedicine，2020，26：100510．DOI：10.1016/j.eclinm.2020.100510.
［39］CORMAN V M，LANDT O，KAISER M，et al．Detection of 2019 novel coronavirus （2019-nCoV） by real-time RT-PCR［J］．Eur Commun Dis Bull，2020，25（3）：2000045．DOI：10.2807/1560-7917.ES.2020.25.3.2000045.
［40］LOHSE S，PFUHL T，BERKó-G?TTEL B，et al．Pooling of samples for testing for SARS-CoV-2 in asymptomatic people［J］．Lancet Infect Dis，2020，20（11）：1231-1232．DOI：10.1016/S1473-3099（20）30362-5.
［41］LECHIEN J R，CHIESA-ESTOMBA C M，DE SIATI D R，et al．
Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease （COVID-19）：a multicenter European study［J］．Eur Arch Otorhinolaryngol，2020，277（8）：2251-2261．DOI：10.1007/s00405-020-05965-1.
［42］MOEIN S T，HASHEMIAN S M，MANSOURAFSHAR B，et al．Smell dysfunction：a biomarker for COVID-19［J］．Int Forum Allergy Rhinol，2020，10（8）：944-950．DOI：10.1002/alr.22587.
［43］LI J W，LONG X，ZHU C L，et al．Olfactory dysfunction in recovered coronavirus disease 2019 （COVID-19） patients［J］．Mov Disord，2020，35（7）：1100-1101．DOI：10.1002/mds.28172.
［44］CHEN M F，SHEN W J，ROWAN N R，et al．Elevated ACE-2 expression in the olfactory neuroepithelium：implications for anosmia and upper respiratory SARS-CoV-2 entry and replication［J］．Eur Respir J，2020，56（3）：2001948．DOI：10.1183/13993003.01948-2020.
［45］LI J W，WANG X Y，ZHU C L，et al．Affected olfaction in COVID-19：Re-defining “asymptomatic”［J］．EClinicalMedicine，2020，29：100628．DOI：10.1016/j.eclinm.2020.100628.
［46］BHATTACHARJEE A S，JOSHI S V，NAIK S，et al．Quantitative assessment of olfactory dysfunction accurately detects asymptomatic COVID-19 carriers［J］．EClinicalMedicine，2020，28：100575．DOI：10.1016/j.eclinm.2020.100575.
［47］Emerging COVID-19 success story：Germany's strong enabling environment［EB/OL］．（2020-06-30）［2020-12-23］．https：//ourworldindata.org/covid-exemplar-germany.

[1]	NIE Daning, SHI Shusheng, TAO Yuru. Clinical Effect of Proprioceptive Neuromuscular Facilitation Technique Combined with Spiral Stabilizing Muscle Chain Training in the Treatment of Adolescent Idiopathic Scoliosis [J]. Chinese General Practice, 2025, 28(24): 3032-3042.
[2]	HE Jinyu, ZHULIDUZI Jiesisibieke, ZHANG Ning, LIU Min, LIANG Wannian. Research on Blood Pressure Control and Its Determinants Among Hypertensive Patients Under Standardized Management in China: Status, Challenges, and Future Directions [J]. Chinese General Practice, 2025, 28(24): 2968-2971.
[3]	ZHOU Qian, WU Xiaomin, WANG Baohua, YAN Ruohan, YU Miao, WU Jing. Study on Nomogram Prediction Model for Risk of Gastric Cancer [J]. Chinese General Practice, 2025, 28(23): 2870-2877.
[4]	YANG Ji, ZHANG Yao, ZHAO Yingqiang, ZHANG Qiuyue. Evaluation of the Effectiveness of TCM Three-level Prevention and Control Model in the Management of Patients with Coronary Heart Disease and Stroke: a Single-center, Prospective Cohort Study [J]. Chinese General Practice, 2025, 28(22): 2750-2761.
[5]	CHEN Youlan, LAN Yanqi, WU Ahua, ZHANG Haixia, HUANG Jiankang, GUO Zhinan. The Health Management Effect of Contracted Family Doctor Services under the Joint Management of Three Teachers in Xiamen City on Elderly Hypertensive Patients [J]. Chinese General Practice, 2025, 28(22): 2769-2775.
[6]	WEN Min, ZHOU Yongling, LIU Jingjing, JIANG Keqing, LIU Juan, ZHU Xiaodan. The Effect and Mechanism of Compensatory Cognitive Training Based on mHealth APP on Stable Schizophrenia Patients [J]. Chinese General Practice, 2025, 28(22): 2819-2825.
[7]	YANG Handan, QIAO Wen, HE Shu, CHEN Yi, TONG Yunmei. The Impact of Acceptance and Commitment Therapy Combined with Sertraline on Depressive Mood, Suicidal Ideation, and Sleep Quality of Adolescents with Depression [J]. Chinese General Practice, 2025, 28(22): 2813-2818.
[8]	WANG Ying, YAN Yijun, LIU Lei, HU Yumin, ZHANG Yang, LIU Kai, JIANG Boren. Effects of Resistance Exercise Combined with Nutritional Intervention on Blood Glucose Stability in Elderly Patients with Type 2 Diabetes Mellitus with Sarcopenia [J]. Chinese General Practice, 2025, 28(21): 2604-2610.
[9]	YANG Jiang, LI Jiansheng, CHEN Yaolong, LIU Huiguo, WANG Jianxin, YU Jiajie, LI Huiru, XIAO Qionghua, XIE Yang, LI Suyun, WANG Minghang. Guideline on Treating Adult Community-acquired Pneumonia with Chinese Patent Medicines (2025 Edition) [J]. Chinese General Practice, 2025, 28(20): 2464-2480.
[10]	ZHOU Yunzhe, MIAO Junxiang, WEI Jiehua, CHEN Lizhang, WANG Tingting. Study on the Association between Polymorphisms and Interaction of CCND1 and CCNE1 Genes with Preeclampsia [J]. Chinese General Practice, 2025, 28(17): 2142-2148.
[11]	JIN Feng, LI Wangling, XIE Fei. Case Sharing of Closed-loop Management Based on the Prevention and Treatment Platform for Chronic Obstructive Pulmonary Disease [J]. Chinese General Practice, 2025, 28(16): 2059-2064.
[12]	DENG Jie, TAO Liyuan, LIU Nan, LI Jun, YAN Wenxin, QIN Chenyuan, LIU Qiao, DU Min, WANG Yaping, LIU Jue. Reliability and Validity of the Chinese Version of the Modified COVID-19 Yorkshire Rehabilitation Scale [J]. Chinese General Practice, 2025, 28(13): 1642-1648.
[13]	YOU Zhanhong, SUN Guozhen, LU Jing, TANG Zhijie, WANG Jie, WANG Qin, WANG Lin. Latent Profile Analysis and Its Influencing Factors of Physical Activity in Patients with Atrial Fibrillation [J]. Chinese General Practice, 2025, 28(12): 1486-1493.
[14]	GUO Xin, ZHOU Mingjuan, FAN Feiting, XIAO Jingmin, CHI Yihe, WU Lei, LIN Lin, CHEN Yuanbin. Acupoint Application with Tianjiu Powder for Pre-asthma: a Randomized Controlled Trial [J]. Chinese General Practice, 2025, 28(11): 1367-1375.
[15]	LI Xiaoze, SUN Guoqiang, SHEN Qiang, SONG Yan, WANG Hufeng. Effectiveness of Individualized Health Education Interventions on Middle-aged and Elderly Patients with Chronic Diseases in the Community: a Cluster Randomized Controlled Trial [J]. Chinese General Practice, 2025, 28(11): 1320-1328.