ABSTRACT
Asymptomatic subjects account for 25 to 45% of SARS-CoV-2 infections, and in particular, subjects on mild immunosuppressive therapy may have symptoms masked and could spread virus for an extended period of time. To determine the cumulative incidence of symptomatic and asymptomatic SARS-CoV-2 infections and associated risk factors, we conducted a prospective clinical and serological survey in a cohort of 278 liver transplant recipients (LTRs) from Central Italy. Three different serology tests were performed every 4 months in 259 LTRs between April 2020 and April 2021: one based on raw extract of whole SARS-CoV-2 virus and two on specific viral antigens (nucleoprotein and receptor binding domain) to detect specific IgG, IgM and IgA. Hundred fifteen LTRs who reported symptoms or close contact with a SARS-CoV-2-positive subject, or had a positive serological result underwent molecular testing by standard screening procedures (RT-PCR on naso-pharyngeal swab). Thirty-one past or active SARS-CoV-2 infections were identified: 14 had positive molecular test (64% symptomatic), and 17 had positive serology only (18% symptomatic). SARS-CoV-2 infection was not statistically related to gender, age, obesity, diabetes, renal impairment, type of anti-rejection therapy or time from transplant. Asymptomatic SARS-CoV-2 cases (61.3%) were more frequent in males and in those with glomerular filtrate rate >50 ml/min. Overall, the addition of repeated serology to standard diagnostic molecular protocols increased detection of SARS-CoV-2 infection from 5.1% to 10.9%. Anti-SARS-CoV-2 seroprevalence among our LTRs (11.2%) is comparable to the general population of Central Italy, considered a medium-impact area. Only one asymptomatic subject (6%) was found to carry SARS-CoV-2 in respiratory tract at the time of serological diagnosis.Copyright © 2021 The Authors
ABSTRACT
By April 28, 2020, the global pandemic of COVID-19 has resulted in over 3 million infections and more than 200, 000 deaths. As the epidemic of COVID-19 has been basically controlled in China, the asymptomatic infection becomes one of most serious challenges for "External defense input, internal defense rebound" currently. Studies have shown that patients with asymptomatic infections are highly contagious in the early stage, most of whom are in the pre-symptomatic stage. Children and pregnant women have a higher incidence of asymptomatic infections, but the impacts are not yet clear. This article reviews the definition, epidemiological characteristics, contagiousness, viral shedding and cause of persistent positive nucleic acid in asymptomatic patients. Active detection of nucleic acids and antibodies and timely diagnosis and treatment of asymptomatic cases are the critical issues for the prevention and control of COVID-19.Copyright © 2020 by the Chinese Medical Association.
ABSTRACT
By April 28, 2020, the global pandemic of COVID-19 has resulted in over 3 million infections and more than 200, 000 deaths. As the epidemic of COVID-19 has been basically controlled in China, the asymptomatic infection becomes one of most serious challenges for "External defense input, internal defense rebound" currently. Studies have shown that patients with asymptomatic infections are highly contagious in the early stage, most of whom are in the pre-symptomatic stage. Children and pregnant women have a higher incidence of asymptomatic infections, but the impacts are not yet clear. This article reviews the definition, epidemiological characteristics, contagiousness, viral shedding and cause of persistent positive nucleic acid in asymptomatic patients. Active detection of nucleic acids and antibodies and timely diagnosis and treatment of asymptomatic cases are the critical issues for the prevention and control of COVID-19.Copyright © 2020 by the Chinese Medical Association.