Editor’s Note: The National Library of Medicine (NLM), on the campus of the National Institutes of Health in Bethesda, Maryland, has been a center of information innovation since its founding in 1836. The world’s largest biomedical library, NLM maintains and makes available a vast print collection and produces electronic information resources on a wide range of topics that are searched billions of times each year by millions of people around the globe. It also supports and conducts research, development, and training in biomedical informatics and health information technology. In addition, the Library coordinates a 6,500-member National Network of Libraries of Medicine that promotes and provides access to health information in communities across the United States.
Background: An ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread around the world. It is debatable whether asymptomatic COVID-19 virus carriers are contagious. We report here a case of the asymptomatic patient and present clinical characteristics of 455 contacts, which aims to study the infectivity of asymptomatic carriers.
Material and methods: 455 contacts who were exposed to the asymptomatic COVID-19 virus carrier became the subjects of our research. They were divided into three groups: 35 patients, 196 family members and 224 hospital staffs. We extracted their epidemiological information, clinical records, auxiliary examination results and therapeutic schedules.
Results: The median contact time for patients was four days and that for family members was five days. Cardiovascular disease accounted for 25% among original diseases of patients. Apart from hospital staffs, both patients and family members were isolated medically. During the quarantine, seven patients plus one family member appeared new respiratory symptoms, where fever was the most common one. The blood counts in most contacts were within a normal range. All CT images showed no sign of COVID-19 infection. No severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections was detected in 455 contacts by nucleic acid test.
Conclusion: In summary, all the 455 contacts were excluded from SARS-CoV-2 infection and we conclude that the infectivity of some asymptomatic SARS-CoV-2 carriers might be weak.
Keywords: Asymptomatic carrier; Contacts; Infectivity; SARS-CoV-2.
Copyright © 2020 Elsevier Ltd. All rights reserved.
Conflict of interest statement
Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
First reported nosocomial outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a pediatric dialysis unit.Clin Infect Dis. 2020 Apr 27:ciaa491. doi: 10.1093/cid/ciaa491. Online ahead of print.PMID: 32337584 Free PMC article.
Features, Evaluation and Treatment Coronavirus (COVID-19).2020 Apr 6. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan–.PMID: 32150360 Free Books & Documents. Review.
The Coronavirus Pandemic: What Does the Evidence Show?J Nepal Health Res Counc. 2020 Apr 19;18(1):1-9. doi: 10.33314/jnhrc.v18i1.2596.PMID: 32335585 Review.
First known person-to-person transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the USA.Lancet. 2020 Apr 4;395(10230):1137-1144. doi: 10.1016/S0140-6736(20)30607-3. Epub 2020 Mar 13.PMID: 32178768 Free PMC article.
First Mildly Ill, Non-Hospitalized Case of Coronavirus Disease 2019 (COVID-19) Without Viral Transmission in the United States – Maricopa County, Arizona, 2020.Clin Infect Dis. 2020 Apr 2:ciaa374. doi: 10.1093/cid/ciaa374. Online ahead of print.PMID: 32240285 Free PMC article.
- Lescure F.X., Bouadma L., Nguyen D. Clinical and virological data of the first cases of COVID-19 in Europe: a case series. Lancet Infect. Dis. 2020 doi: 10.1016/S1473-3099(20)30200-0. Published Online March 27 2020. Available at: – DOI
- Adalja A.A., Toner E., Inglesby T.V. JAMA; 2020. Priorities for the US Health Community Responding to COVID-19. Published Online March 03 2020. Available at: – DOI
- World Health Organization . 2020. Coronavirus Disease (COVID-19) Outbreak.https://www.who.int/emergencies/diseases/novel-coronavirus-2019 Available at:
Source: National Library of Medicine