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Antibody seroconversion in asymptomatic and symptomatic patients infected with severe acute respiratory syndrome coronavirus 2 (SARS?CoV?2)

ABSTRACT: Abstract Objectives Asymptomatic and symptomatic patients may transmit severe acute respiratory syndrome coronavirus 2 (SARS?CoV?2), but their clinical features and immune responses remain largely unclear. We aimed to characterise the clinical features and immune responses of asymptomatic and symptomatic patients infected with SARS?CoV?2. Methods We collected clinical, laboratory and epidemiological records of patients hospitalised in a coronavirus field hospital in Wuhan. We performed qualitative detection of anti?SARS?CoV?2 immunoglobulin M (IgM) and immunoglobulin G (IgG) using archived blood samples. Results Of 214 patients with SARS?CoV?2, 26 (12%) were asymptomatic at hospital admission and during hospitalisation. Most asymptomatic patients were ? 60 years (96%) and females (65%) and had few comorbidities (< 16%). Serum levels of white and red blood cells were higher in asymptomatic than in symptomatic patients (P?values < 0.05). During hospitalisation, IgG seroconversion was commonly observed in both asymptomatic and symptomatic patients (85% versus 94%, P?value = 0.07); in contrast, IgM seroconversion was less common in asymptomatic than in symptomatic patients (31% versus 74%, P?value < 0.001). The median time from the first virus?positive screening to IgG or IgM seroconversion was significantly shorter in asymptomatic than in symptomatic patients (median: 7 versus 14 days, P?value < 0.01). Furthermore, IgG/IgM seroconversion rates increased concomitantly with the clearance of SARS?CoV?2 in both asymptomatic and symptomatic patients. At the time of virus clearance, IgG/IgM titres and plasma neutralisation capacity were significantly lower in recovered asymptomatic than in recovered symptomatic patients (P?values < 0.01). Conclusion Asymptomatic and symptomatic patients exhibited different kinetics of IgG/IgM responses to SARS?CoV?2. Asymptomatic patients may transmit SARS?CoV?2, highlighting the importance of early diagnosis and treatment. We studied a cohort of 26 asymptomatic and 188 symptomatic patients in a coronavirus field hospital. We found asymptomatic cases, mostly young females ? 60 years, in approximately 12% of nonseverely ill cases. More than 90% of cases experienced immunoglobulin M (IgM)/immunoglobulin G (IgG) seroconversion at the time of virus clearance, whereas the median time from the first virus?positive tests to IgG/IgM seroconversion was significantly shorter in asymptomatic than in symptomatic patients. Compared with symptomatic patients, asymptomatic patients had lower IgG/IgM titres and plasma neutralisation capacity at the time of virus clearance.

SUBMITTER: Jiang C

PROVIDER: S-EPMC7519951 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe role of SARS-Cov-2-infected persons who develop symptoms after testing (presymptomatics) or not at all (asymptomatics) in the pandemic spread is unknown.ObjectivesTo determine infectiousness and probable contribution of asymptomatic persons (at the time of testing) to pandemic SARS-CoV-2 spread.Data sourcesLitCovid, medRxiv, Google Scholar, and WHO Covid-19 databases (to 31 March 2021) and references in included studies.Study eligibility criteriaStudies with a proven or hypothesized transmission chain based either on serial PCR cycle threshold readings and/or viral culture and/or gene sequencing, with adequate follow-up.ParticipantsPeople exposed to SARS-CoV-2 within 2-14 days to index asymptomatic (at time of observation) infected individuals.InterventionsReliability of symptom and signs was assessed within contemporary knowledge; transmission likelihood was assessed using adapted causality criteria.MethodsSystematic review. We contacted all included studies' corresponding authors requesting further details.ResultsWe included 18 studies from a diverse setting with substantial methodological variation (this field lacks standardized methodology). At initial testing, prevalence of asymptomatic cases was 12.5-100%. Of these, 6-100% were later determined to be presymptomatic, this proportion varying according to setting, methods of case ascertainment and population. Nursing/care home facilities reported high rates of presymptomatic: 50-100% (n = 3 studies). Fourteen studies were classified as high risk of, and four studies as at moderate risk of symptom ascertainment bias. High-risk studies may be less likely to distinguish between presymptomatic and asymptomatic cases. Six asymptomatic studies and four presymptomatic studies reported culturing infectious virus; data were too sparse to determine infectiousness duration. Three studies provided evidence of possible and three of probable/likely asymptomatic transmission; five studies provided possible and two probable/likely presymptomatic SARS-CoV-2 transmission.ConclusionHigh-quality studies provide probable evidence of SARS-CoV-2 transmission from presymptomatic and asymptomatic individuals, with highly variable estimated transmission rates.

Project description:ObjectivesStudies comparing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA load in the upper respiratory tract (URT) between children and adults-who either presented with coronavirus disease 2019 (COVID-19) or were asymptomatic-have yielded inconsistent results. Here, we conducted a retrospective, single-centre study to address this issue.Patients and methodsIncluded were 1184 consecutive subjects (256 children and 928 adults) testing positive for SARS-CoV-2 RNA in nasopharyngeal exudates (NPs); of these, 424 (121 children and 303 adults) had COVID-19 and 760 (135 children and 625 adults) were asymptomatic close contacts of COVID-19 patients. SARS-CoV-2 RNA testing was carried out using the TaqPath COVID-19 Combo Kit (Thermo Fisher Scientific, MS, USA). The AMPLIRUN® TOTAL SARS-CoV-2 RNA Control (Vircell SA, Granada, Spain) was used for estimating SARS-CoV-2 RNA loads (in copies/mL). SARS-CoV-2 RNA loads at the time of laboratory diagnosis (single specimen/patient) were used for comparison purposes.ResultsMedian initial SARS-CoV-2 RNA load was lower (p 0.094) in children (6.98 log10 copies/mL, range 3.0-11.7) than in adults (7.14 log10 copies/mL, range 2.2-13.4) with COVID-19. As for asymptomatic individuals, median SARS-CoV-2 RNA load was comparable (p 0.97) in children (6.20 log10 copies/mL, range 1.8-11.6) and adults (6.48 log10 copies/mL, range 1.9-11.8). Children with COVID-19 symptoms displayed SARS-CoV-2 RNA loads (6.98 log10 copies/mL, range 3.0-11.7) comparable to those of their asymptomatic counterparts (6.20 log10 copies/mL, range 1.8-11.6) (p 0.61). Meanwhile in adults, median SARS-CoV-2 RNA load was significantly higher in symptomatic (7.14 log10 copies/mL, range 2.2-13.4) than in asymptomatic subjects (6.48 log10 copies/mL, range 1.9-11.8) (p < 0.001). Overall, the observed URT SARS-CoV-2 RNA clearance rate was faster in children than in adults.ConclusionsBased on viral load data at the time of diagnosis, our results suggest that SARS-CoV-2-infected children, with or without COVID-19, may display NP viral loads of comparable magnitude to those found in their adult counterparts. However, children may have shorter viral shedding than adults.

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Antibody seroconversion in asymptomatic and symptomatic patients infected with severe acute respiratory syndrome coronavirus 2 (SARS?CoV?2)

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