New challenge of asymptomatic infections from COVID-19: current scenario

Nidhi Verma, Vikas Verma, Harish Kumar Sagar, Neha Singh, Veer Karuna, Priya Gupta, Anshu Singh


Since the outbreak of coronavirus 2019 (COVID-19) disease in China, late December 2019, it took a substantial detriment and challenges for more than 200 countries worldwide. Recently with the upcoming insights about etiology of the virus, there is increasing evidence that many patients with COVID-19 are asymptomatic or they have only mild symptoms, but they act as carrier and are able to transmit the virus to others. There are technical difficulties in screening for these asymptomatic infections, which makes it even more challenging for any nation to control this epidemic. This article reviews entry & replication of the virus, pathogenesis, asymptomatic infections, dissemination, prevention, control & treatment in asymptomatic infections with COVID-19, expecting it would be helpful for early prevention and containment of this severe public health threat worldwide.


COVID-19, Current scenario, Asymptomatic infections

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Novel coronavirus (2019-nCov) – Situation Report 22. Geneva: World Health Organization; 11 February 2020. Available at: ncov.pdf?sfvrsn=fb6d49b1_2. Accessed on 22 May 2020.


WHO. Coronavirus disease 2019 (COVID-19). 2020. Situation Report-100. Available at: emergencies/ diseases/ novel-coronavirus-2019/ situation-reports. Accessed on 20 May 2020.

WHO. Clinical management of severe acute respiratory infection (SARI) when COVID-19 disease is suspected. 2020. Available at: management- of-severe-acute-respiratory- infection-when novel- coronavirus-(ncov)-infection-is-suspected. Accessed on 20 May 2020.

WHO: use of chest imaging in covid-19: a rapid advice guide; 11 JUNE 2020. Accessed on 20 May 2020.

10th July 2020, Worldo meter 2020; United Nations Geoscheme. › coronavirus.

WHO. Laboratory diagnostics for novel coronavirus. 2020. Available at: guidance/ laboratory. Accessed on 20 May 2020.

Zhou P, Yang XL, Wang XG, Hu B, Zhang L, Zhang W, et al. A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature. 2020;579(7798):270-3.

Hoffmann M, Kleine-Weber H, Schroeder S, Krüger N, Herrler T, Erichsen S et al. SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease inhibitor. Cell. 181:1-10.

Corbett KS, Goldsmith JA, Hsieh CL, Abiona O, Graham BS, McLellan JS. Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation. Science. 367(6483):1260-3.

Coutard B, Valle C, de Lamballerie X, Canard B, Seidah NG, Decroly E. The spike glycoprotein of the new coronavirus 2019-nCoV contains a furin-like cleavage site absent in CoV of the same clade. Antivir Res 2020;176:104742.

Matsuyama S, Taguchi F. Two-step conformational changes in a coronavirus envelope glycoprotein mediated by receptor binding and proteolysis. J Virol. 2009;83(21):11133-41.

Xu Z, Shi L, Wang Y, Zhang J, Huang L, Zhang C, et al. Pathological findings of COVID-19 associated with acute respiratory distress syndrome. Lancet Respir Med. 2020;8(4):420-2.

Tian S, Hu W, Niu L, Liu H, Xu H, Xiao SY. Pulmonary pathology of early-phase 2019 novel coronavirus (COVID-19) pneumonia in two patients with lung cancer. J Thorac Oncol. 2020;S1556-0864(20):30132-5.

COVID-19 Case Tracker. Johns Hopkins Coronavirus Resource Center. 2020. Accessed at Accessed on 26May 2020.

Chen Y, Wang AH, Yi B, Ding KQ, Wang HB, Wang JM, et al. The epidemiological characteristics of infection in close contacts of COVID-19 in Ningbo city. Chin J Epidemiol. 2020:41.

Nishiura H, Kobayashi T, Suzuki A, Jung SM, Hayashi K, Kinoshita R, et al. Estimation of the asymptomatic ratio of novel coronavirus infections (COVID-19). Int J Infect Dis. 2020;94:154-5.

Bai Y, Yao L, Wei T, Tian F, Jin DY, Chen L, et al. Presumed asymptomatic carrier transmission of COVID-19. J Am Med Assoc. 2020;323(14):1406-7.

Kimball A, Hatfield KM, Arons M, James A, Taylor J, Spicer K, et al. Asymptomatic and presymptomatic SARS-CoV-2 infections in residents of a long-term care skilled nursing facility- king county, Washington, march 2020. Morb Mortal Wkly Rep. 2020;69(13):377e81.

Gao WJ, Li LM. Advances on presymptomatic or asymptomatic carrier transmission of COVID-19. Chin J Epidemiol. 2020;41(4):485-8.

Shen M, Zhou Y, Ye J, Abdullah Al-Maskri AA, Kang Y, Zeng S, et al. Recent advances and perspectives of nucleic acid detection for coronavirus. J Pharm Anal. 2020;10(2):97-101.

Wolfel R, Corman VM, Guggemos W, Seilmaier M, Zange S, Muller MA, et al. Virological assessment of hospitalized patients with COVID-2019. Nature 2020. Available at: Accessec on 20 May 2020.

An JH, Liao XJ, Xiao TY, Qian S, Yuan J, Ye HC, et al. Clinical characteristics of the recovered COVID-19 patients with redetectable positive RNA test. medRxiv 2020.

Hu Z, Song C, Xu C, Jin G, Chen Y, Xu X, et al. Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. Sci China Life Sci. 2020;63(5):706-11.

Pan Y, Yu X, Du X, Li Q, Li X, Qin T, et al. Epidemiological and clinical characteristics of 26 asymptomatic SARS-CoV-2 carriers. J Infect Dis. 2020.

Gao WJ, Zheng K, Ke J, Li LM. Advances on the asymptomatic infection of COVID-19. Chin J Epidemiol. 2020:41.

Chan JF, Yuan S, Kok KH, To KK, Chu H, Yang J, et al. A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster. Lancet. 2020; 395(10223):514-23.

Lu S, Lin J, Zhang Z, Xiao L, Jiang Z, Chen J, et al. Alert for nonrespiratory symptoms of Coronavirus Disease 2019 (COVID-19) patients in epidemic period: a case report of familial cluster with three asymptomatic COVID-19 patients. Med Virol. 2020.

Wang Y, Liu Y, Liu L, Wang X, Luo N, Ling L. Clinical outcome of 55 asymptomatic cases at the time of hospital admission infected with SARS-Coronavirus-2 in Shenzhen, China. J Infect Dis. 2020;221(11):1770-4.

Rothe C, Schunk M, Sothmann P, Bretzel G, Froeschl G, Wallrauch C, et al. Transmission of 2019-nCoV infection from an asymptomatic contact in Germany. N Engl J Med. 2020;382(10):970-1.

Lan L, Xu D, Ye G, Xia C, Wang S, Li Y, et al. Positive RT-PCR test results in patients recovered from COVID-19. J Am Med Assoc. 2020; 323(15):1502-3.

Ai T, Yang Z, Hou H, Zhan C, Chen C, Lv W, et al. Correlation of chest CT and RT-PCR testing in coronavirus disease 2019(COVID-19) in China: a report of 1014 cases. Radiology. 2020:200642.

Chen J, Ling Y, Xi XH, Liu P, Li F, Li T, et al. Efficacies of lopinavir/ritonavir and abidol in the treatment of novel coronavirus pneumonia (in Chinese). Chin J Infect Dis. 2020;38(2):86-9.

Luo SH, Liu W, Liu ZJ, Zheng XY, Hong CX, Liu ZR, et al. A confirmed asymptomatic carrier of 2019 novel coronavirus (SARS-CoV-2). Chin Med J. 2020;133(9):1123-5.

National Health Commission of People’s Republic of China. Diagnostic and treatment plan of Coronavirus disease 2019. 7th ed. 2020. Tentative. Available at: s7653p/202003/46c9294. Accessed on 20 May 2020.

Sutiningsih D, Rahatina VE, Prabowo Y, Haryanto A, Wibowo MA. Epidemiologic and Clinical Characteristics of Patients with Covid-19 in Central Java, Indonesia. InE3S Web of Conferences. 2020;202:12014).

Day M. Covid-19: four fifths of cases are asymptomatic, China figures indicate. Bio Med J. 2020;369:m1375

Mizumoto K, Kagaya K, Zarebski A, Chowell G. Estimating the asymptomatic proportion of coronavirus disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship, Yokohama, Japan, 2020. Eurosurveillance. 2020;25(10):2000180.

Ki M. Epidemiologic characteristics of early cases with 2019 novel coronavirus (2019-nCoV) disease in Korea. Epidemiology and health. 2020;42.