face mask-coronavirus-quarantine-covid19

COVID-19: Asymptomatic Individuals May Be Driving Pandemic

MedicalResearch.com Interview with:
Joon Seo Lim, PhD, ELS
Clinical Research Center
Asan Institute for Life Sciences
Asan Medical Center, Songpa-gu
Seoul, Republic of Korea

MedicalResearch.com: What is the background for this study?

Response: The COVID-19 pandemic is continuing to spread at an alarming rate in all parts of the world, and screening individuals based on symptoms (e.g., fever, cough, anosmia) does not seem to be effective in sufficiently curbing the transmission of the disease. This suggests that asymptomatic individuals infected with SARS-CoV-2 may be a driving force of the ongoing pandemic, but empirical evidence on this issue has been lacking because asymptomatic individuals are likely to go unnoticed unless subjected to systematic contact tracing. A large-sized outbreak of COVID-19 from a single religious group in South Korea enabled us to identify and test a large number of asymptomatic individuals with SARS-CoV-2 alongside symptomatic patients from the same cluster. 

MedicalResearch.com: What are the main findings?

Response: We were first surprised to find that almost one-fifth of the study cohort remained asymptomatic from potential exposure to SARS-CoV-2 until laboratory confirmation. Importantly, we found that such asymptomatic individuals had a considerable amount of SARS-CoV-2 viral load in their upper respiratory tract and that their viral load was comparable to that in symptomatic patients. Moreover, more than half of the asymptomatic individuals and symptomatic patients continued to show positive results in SARS-CoV-2 tests even after 13 days from diagnosis, which suggests that SARS-CoV-2 has a notably protracted course than that initially hypothesized.

MedicalResearch.com: What should readers take away from your report?

face mask-coronavirus-quarantine-covid19Response: Asymptomatic individuals with SARS-CoV-2 infection may indeed be contributing to the community spread of COVID-19. Therefore, the use of face masks by the general public—regardless of the presence of symptoms—should be highly recommended along with strict social and physical distancing. 

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: Our study results were based on positive findings in RT-PCR for SARS-CoV-2 genes. However, positive PCR results do not necessarily indicate the presence of viable virus with infectious capabilities. Therefore, future studies should focus on whether asymptomatic individuals with SARS-CoV-2 infection are able to shed viable particles of SARS-CoV-2, and if so, how soon and how long such viral shedding is possible should also be investigated.

The authors have no disclosures.


Ra SH, Lim JS, Kim G, et al
Upper respiratory viral load in asymptomatic individuals and mildly symptomatic patients with SARS-CoV-2 infection
Thorax Published Online First: 22 September 2020. doi: 10.1136/thoraxjnl-2020-215042


Last Modified: [last-modified] 

The information on MedicalResearch.com is provided for educational purposes only, and is in no way intended to diagnose, cure, or treat any medical or other condition. Always seek the advice of your physician or other qualified health and ask your doctor any questions you may have regarding a medical condition. In addition to all other limitations and disclaimers in this agreement, service provider and its third party providers disclaim any liability or loss in connection with the content provided on this website.


Last Updated on September 23, 2020 by Marie Benz MD FAAD