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1.
Front Immunol ; 12: 728021, 2021.
Article in English | MEDLINE | ID: covidwho-1538370

ABSTRACT

As the COVID-19 pandemic continues, the authorization of vaccines for emergency use has been crucial in slowing down the rate of infection and transmission of the SARS-CoV-2 virus that causes COVID-19. In order to investigate the longitudinal serological responses to SARS-CoV-2 natural infection and vaccination, a large-scale, multi-year serosurveillance program entitled SPARTA (SARS SeroPrevalence and Respiratory Tract Assessment) was initiated at 4 locations in the U.S. The serological assay presented here measuring IgG binding to the SARS-CoV-2 receptor binding domain (RBD) detected antibodies elicited by SARS-CoV-2 infection or vaccination with a 95.5% sensitivity and a 95.9% specificity. We used this assay to screen more than 3100 participants and selected 20 previously infected pre-immune and 32 immunologically naïve participants to analyze their antibody binding to RBD and viral neutralization (VN) responses following vaccination with two doses of either the Pfizer-BioNTech BNT162b2 or the Moderna mRNA-1273 vaccine. Vaccination not only elicited a more robust immune reaction than natural infection, but the level of neutralizing and anti-RBD antibody binding after vaccination is also significantly higher in pre-immune participants compared to immunologically naïve participants (p<0.0033). Furthermore, the administration of the second vaccination did not further increase the neutralizing or binding antibody levels in pre-immune participants (p=0.69). However, ~46% of the immunologically naïve participants required both vaccinations to seroconvert.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Immunogenicity, Vaccine , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccination , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19/diagnosis , COVID-19/immunology , COVID-19/virology , COVID-19 Serological Testing , COVID-19 Vaccines/immunology , Enzyme-Linked Immunosorbent Assay , Female , Humans , Male , Middle Aged , Time Factors , United States , Young Adult
2.
J Assist Reprod Genet ; 38(2): 539-541, 2021 02.
Article in English | MEDLINE | ID: covidwho-1530350
4.
Saudi Med J ; 42(7): 742-749, 2021 Jul.
Article in English | MEDLINE | ID: covidwho-1513260

ABSTRACT

OBJECTIVES: To identify the prevalence of COVID-19 antibodies among operating room and critical care staff. METHODS: In this cross-sectional study, we recruited 319 Healthcare workers employed in the operation theater and intensive care unit of King Abdulaziz University Hospital (KAUH), a tertiary teaching hospital in Jeddah, Saudi Arabia between August 9, 2020 and November 2, 2020. All participants completed a 20-item questionnaire on demographic data and COVID-19 risk factors and provided blood samples. Antibody testing was performed using an in-house enzyme immunoassay and microneutralization test. RESULTS: Of the 319 participants, 39 had detectable COVID-19 antibodies. Five of them had never experienced any symptoms suggestive of COVID-19, and only 19 were previously diagnosed with COVID-19. The odds of developing COVID-19 or having corresponding antibodies increased if participants experienced COVID-19 symptoms (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.2-7.5) or reported contact with an infected family member (OR, 5.3; 95% CI, 2.5-11.2). Disease acquisition was not associated with employment in the ICU and involvement in the intubation of or close contact with COVID-19 patients. Of the 19 previously diagnosed participants, 6 did not possess any detectable COVID-19 antibodies. CONCLUSIONS: Healthcare workers may have undiagnosed COVID-19, and those previously infected may not have long-lasting immunity. Therefore, hospitals must continue to uphold strict infection control during the COVID-19 pandemic.


Subject(s)
COVID-19 Serological Testing/statistics & numerical data , COVID-19/diagnosis , Health Personnel , SARS-CoV-2/isolation & purification , Adult , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/epidemiology , Critical Care , Cross-Sectional Studies , Enzyme-Linked Immunosorbent Assay , Female , Hospitals, Teaching , Humans , Infectious Disease Transmission, Patient-to-Professional , Male , Middle Aged , Operating Rooms , Pandemics , Prevalence , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/genetics , Saudi Arabia/epidemiology
5.
PLoS One ; 16(11): e0259823, 2021.
Article in English | MEDLINE | ID: covidwho-1506297

ABSTRACT

BACKGROUND: Pediatric SARS-CoV-2 data remain limited and seropositivity rates in children were reported as <1% early in the pandemic. Seroepidemiologic evaluation of SARS-CoV-2 in children in a major metropolitan region of the US was performed. METHODS: Children and adolescents ≤19 years were enrolled in a cross-sectional, observational study of SARS-CoV-2 seroprevalence from July-October 2020 in Northern Virginia, US. Demographic, health, and COVID-19 exposure information was collected, and blood analyzed for SARS-CoV-2 spike protein total antibody. Risk factors associated with SARS-CoV-2 seropositivity were analyzed. Orthogonal antibody testing was performed, and samples were evaluated for responses to different antigens. RESULTS: In 1038 children, the anti-SARS-CoV-2 total antibody positivity rate was 8.5%. After multivariate logistic regression, significant risk factors included Hispanic ethnicity, public or absent insurance, a history of COVID-19 symptoms, exposure to person with COVID-19, a household member positive for SARS-CoV-2 and multi-family or apartment dwelling without a private entrance. 66% of seropositive children had no symptoms of COVID-19. Secondary analysis included orthogonal antibody testing with assays for 1) a receptor binding domain specific antigen and 2) a nucleocapsid specific antigen had concordance rates of 80.5% and 79.3% respectively. CONCLUSIONS: A much higher burden of SARS-CoV-2 infection, as determined by seropositivity, was found in children than previously reported; this was also higher compared to adults in the same region at a similar time. Contrary to prior reports, we determined children shoulder a significant burden of COVID-19 infection. The role of children's disease transmission must be considered in COVID-19 mitigation strategies including vaccination.


Subject(s)
COVID-19/blood , COVID-19/epidemiology , SARS-CoV-2 , Adolescent , Antibodies, Viral/blood , Antigens, Viral , COVID-19/immunology , COVID-19 Serological Testing , Child , Child, Preschool , Cross-Sectional Studies , Female , Humans , Infant , Infant, Newborn , Male , Multivariate Analysis , Pandemics , Risk Factors , Seroepidemiologic Studies , United States
6.
J Clin Microbiol ; 59(9): e0099121, 2021 08 18.
Article in English | MEDLINE | ID: covidwho-1501533

ABSTRACT

Antigen-based rapid diagnostic tests (RDTs) are used in children despite the lack of data. We evaluated the diagnostic performance of the Panbio-COVID-19 Ag Rapid Test Device (P-RDT) in children. Symptomatic and asymptomatic participants 0 to 16 years old had two nasopharyngeal swabs (NPS) for both reverse transcription-PCR (RT-PCR) and P-RDT. A total of 822 participants completed the study, of which 533 (64.9%) were symptomatic. Among the 119 (14.5%) RT-PCR-positive patients, the P-RDT sensitivity was 0.66 (95% confidence interval [CI] 0.57 to 0.74). Mean viral load (VL) was higher among P-RDT-positive patients than negative ones (P < 0.001). Sensitivity was 0.91 in specimens with VL of >1.0E6 IU/ml (95% CI 0.83 to 0.99) and decreased to 0.75 (95% CI 0.66 to 0.83) for specimens >1.0E3 IU/ml. Among symptomatic participants, the P-RDT displayed a sensitivity of 0.73 (95% CI 0.64 to 0.82), which peaked at 1.00 at 2 days post-onset of symptoms (DPOS) (95% CI 1.00 to 1.00), then decreased to 0.56 (95% CI 0.23 to 0.88) at 5 DPOS. There was a trend toward lower P-RDT sensitivity in symptomatic children <12 years (0.62 [95% CI 0.45 to 0.78]) versus ≥12 years (0.80 [95% CI 0.69 to 0.91]; P = 0.09). In asymptomatic participants, the P-RDT displayed a sensitivity of 0.43 (95% CI 0.26 to 0.61). Specificity was 1.00 in symptomatic and asymptomatic children (95% CI 0.99 to 1.00). The overall 73% and 43% sensitivities of P-RDT in symptomatic and asymptomatic children, respectively, was below the 80% cutoff recommended by the World Health Organization. We observed a correlation between VL and P-RDT sensitivity, as well as variation of sensitivity according to DPOS, a major determinant of VL. These data highlight the limitations of RDTs in children, with the potential exception in early symptomatic children ≥12yrs.


Subject(s)
COVID-19 , SARS-CoV-2 , Adolescent , Antigens, Viral , COVID-19 Serological Testing , Child , Child, Preschool , Humans , Infant , Infant, Newborn , Sensitivity and Specificity
7.
Clin Microbiol Rev ; 34(3)2021 06 16.
Article in English | MEDLINE | ID: covidwho-1501523

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory disease coronavirus 2 (SARS-CoV-2), has led to millions of confirmed cases and deaths worldwide. Efficient diagnostic tools are in high demand, as rapid and large-scale testing plays a pivotal role in patient management and decelerating disease spread. This paper reviews current technologies used to detect SARS-CoV-2 in clinical laboratories as well as advances made for molecular, antigen-based, and immunological point-of-care testing, including recent developments in sensor and biosensor devices. The importance of the timing and type of specimen collection is discussed, along with factors such as disease prevalence, setting, and methods. Details of the mechanisms of action of the various methodologies are presented, along with their application span and known performance characteristics. Diagnostic imaging techniques and biomarkers are also covered, with an emphasis on their use for assessing COVID-19 or monitoring disease severity or complications. While the SARS-CoV-2 literature is rapidly evolving, this review highlights topics of interest that have occurred during the pandemic and the lessons learned throughout. Exploring a broad armamentarium of techniques for detecting SARS-CoV-2 will ensure continued diagnostic support for clinicians, public health, and infection prevention and control for this pandemic and provide advice for future pandemic preparedness.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19 Serological Testing/methods , COVID-19/diagnostic imaging , COVID-19/diagnosis , SARS-CoV-2/genetics , Biosensing Techniques , Genome, Viral/genetics , Humans , Nucleic Acid Amplification Techniques/methods , Point-of-Care Testing , SARS-CoV-2/immunology , Specimen Handling/methods
8.
JAMA Netw Open ; 4(11): e2132563, 2021 11 01.
Article in English | MEDLINE | ID: covidwho-1499193

ABSTRACT

Importance: Although several studies have provided information on short-term clinical outcomes in children with perinatal exposure to SARS-CoV-2, data on the immune response in the first months of life among newborns exposed to the virus in utero are lacking. Objective: To characterize systemic and mucosal antibody production during the first 2 months of life among infants who were born to mothers infected with SARS-CoV-2. Design, Setting, and Participants: This prospective cohort study enrolled 28 pregnant women who tested positive for SARS-CoV-2 infection and who gave birth at Policlinico Umberto I in Rome, Italy, from November 2020 to May 2021, and their newborns. Maternal and neonatal systemic immune responses were investigated by detecting spike-specific antibodies in serum, and the mucosal immune response was assessed by measuring specific antibodies in maternal breastmilk and infant saliva 48 hours after delivery and 2 months later. Exposures: Maternal infection with SARS-CoV-2 in late pregnancy. Main Outcomes and Measures: The systemic immune response was evaluated by the detection of SARS-CoV-2 IgG and IgA antibodies and receptor binding domain-specific IgM antibodies in maternal and neonatal serum. The mucosal immune response was assessed by measuring spike-specific antibodies in breastmilk and in infant saliva, and the presence of antigen-antibody spike IgA immune complexes was investigated in breastmilk samples. All antibodies were detected using an enzyme-linked immunosorbent assay. Results: In total, 28 mother-infant dyads (mean [SD] maternal age, 31.8 [6.4] years; mean [SD] gestational age, 38.1 [2.3] weeks; 18 [60%] male infants) were enrolled at delivery, and 21 dyads completed the study at 2 months' follow-up. Because maternal infection was recent in all cases, transplacental transfer of virus spike-specific IgG antibodies occurred in only 1 infant. One case of potential vertical transmission and 1 case of horizontal infection were observed. Virus spike protein-specific salivary IgA antibodies were significantly increased (P = .01) in infants fed breastmilk (0.99 arbitrary units [AU]; IQR, 0.39-1.68 AU) vs infants fed an exclusive formula diet (0.16 AU; IQR, 0.02-0.83 AU). Maternal milk contained IgA spike immune complexes at 48 hours (0.53 AU; IQR, 0.25-0.39 AU) and at 2 months (0.09 AU; IQR, 0.03-0.17 AU) and may have functioned as specific stimuli for the infant mucosal immune response. Conclusions and Relevance: In this cohort study, SARS-CoV-2 spike-specific IgA antibodies were detected in infant saliva, which may partly explain why newborns are resistant to SARS-CoV-2 infection. Mothers infected in the peripartum period appear to not only passively protect the newborn via breastmilk secretory IgA but also actively stimulate and train the neonatal immune system via breastmilk immune complexes.


Subject(s)
COVID-19/immunology , Immunoglobulin A/immunology , Milk, Human/immunology , Pregnancy Complications, Infectious/immunology , Adult , COVID-19/blood , COVID-19/transmission , COVID-19 Serological Testing , Female , Humans , Immunoglobulin A/isolation & purification , Immunoglobulin G/immunology , Immunoglobulin G/isolation & purification , Infant , Infant, Newborn , Infectious Disease Transmission, Vertical/prevention & control , Male , Pregnancy , Pregnancy Complications, Infectious/blood , Prospective Studies , SARS-CoV-2 , Saliva/immunology , Spike Glycoprotein, Coronavirus/immunology
9.
J Coll Physicians Surg Pak ; 31(1): S55-S56, 2021 Jan.
Article in English | MEDLINE | ID: covidwho-1498351

ABSTRACT

ABSTARCT Four hundred and fifty-three SARS CoV-2 antibodies tests were conducted using Roche Elecsys® Anti SARS CoV-2 kits (detecting total antibodies) between June 13 to July 8, 2020 (25 days) on Cobas® e411 automatic analyser, based on electrochemiluminescence immunoassay (ECLIA) principle. Samples were collected from walk-in patients at our facility. Among them, 2 (0.4%) were found equivocal, 289 (63.8%) were found reactive, while 162 (35.8%) were found non-reactive. Moreover, reactive (symptomatic) cases were 262 (57.8%), reactive (asymptomatic) were 27 (6.0%), non-reactive (symptomatic) were 34 (7.5%), while non-reactive (asymptomatic) were 128 (28.3%). Most common symptom was fever, found in 262 (87.9%) individuals, followed by dry cough 146 (49.0%). Most number of reactive cases, i.e. 110 (42.6%) were those who got themselves tested between 15-21 days after onset of first symptom. Key Words: COVID-19, Coronavirus, Antibodies testing.


Subject(s)
COVID-19 , Antibodies, Viral , COVID-19 Serological Testing , Humans , Immunoglobulin G , SARS-CoV-2 , Sensitivity and Specificity
10.
Ann Intern Med ; 174(8): 1081-1089, 2021 08.
Article in English | MEDLINE | ID: covidwho-1497803

ABSTRACT

BACKGROUND: Evidence to understand effective strategies for surveillance and early detection of SARS-CoV-2 is limited. OBJECTIVE: To describe the results of a rigorous, large-scale COVID-19 testing and monitoring program. DESIGN: The U.S. National Football League (NFL) and the NFL Players Association (NFLPA) instituted a large-scale COVID-19 monitoring program involving daily testing using 2 reverse transcription polymerase chain reaction (RT-PCR) platforms (Roche cobas and Thermo Fisher QuantStudio), a transcription-mediated amplification platform (Hologic Panther), and an antigen point-of-care (aPOC) test (Quidel Sofia). SETTING: 32 NFL clubs in 24 states during the 2020 NFL season. PARTICIPANTS: NFL players and staff. MEASUREMENTS: SARS-CoV-2 test results were described in the context of medically adjudicated status. Cycle threshold (Ct) values are reported when available. RESULTS: A total of 632 370 tests administered across 11 668 persons identified 270 (2.4%) COVID-19 cases from 1 August to 14 November 2020. Positive predictive values ranged from 73.0% to 82.0% across the RT-PCR platforms. High Ct values (33 to 37) often indicated early infection. For the first positive result, the median Ct value was 32.77 (interquartile range, 30.02 to 34.72) and 22% of Ct values were above 35. Among adjudicated COVID-19 cases tested with aPOC, 42.3% had a negative result. Positive concordance between aPOC test result and adjudicated case status increased as viral load increased. LIMITATIONS: Platforms varied by laboratory, and test variability may reflect procedural differences. CONCLUSION: Routine RT-PCR testing allowed early detection of infection. Cycle threshold values provided a useful guidepost for understanding results, with high values often indicating early infection. Antigen POC testing was unable to reliably rule out COVID-19 early in infection. PRIMARY FUNDING SOURCE: The NFL and the NFLPA.


Subject(s)
COVID-19 Nucleic Acid Testing , COVID-19 Serological Testing , COVID-19/diagnosis , Football , Occupational Health , COVID-19/epidemiology , Early Diagnosis , Humans , Incidence , SARS-CoV-2 , United States/epidemiology
11.
Microbiol Spectr ; 9(2): e0105921, 2021 10 31.
Article in English | MEDLINE | ID: covidwho-1495012

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in late 2019 and has since caused a global pandemic resulting in millions of cases and deaths. Diagnostic tools and serological assays are critical for controlling the outbreak, especially assays designed to quantitate neutralizing antibody levels, considered the best correlate of protection. As vaccines become increasingly available, it is important to identify reliable methods for measuring neutralizing antibody responses that correlate with authentic virus neutralization but can be performed outside biosafety level 3 (BSL3) laboratories. While many neutralizing assays using pseudotyped virus have been developed, there have been few studies comparing the different assays to each other as surrogates for authentic virus neutralization. Here, we characterized three enzyme-linked immunosorbent assays (ELISAs) and three pseudotyped vesicular stomatitis virus (VSV) neutralization assays and assessed their concordance with authentic virus neutralization. The most accurate assays for predicting authentic virus neutralization were luciferase- and secreted embryonic alkaline phosphatase (SEAP)-expressing pseudotyped virus neutralizations, followed by green fluorescent protein (GFP)-expressing pseudotyped virus neutralization, and then the ELISAs. IMPORTANCE The ongoing COVID-19 pandemic is caused by infection with severe acute respiratory syndrome virus 2 (SARS-CoV-2). Prior infection or vaccination can be detected by the presence of antibodies in the blood. Antibodies in the blood are also considered to be protective against future infections from the same virus. The "gold standard" assay for detecting protective antibodies against SARS-CoV-2 is neutralization of authentic SARS-CoV-2 virus. However, this assay can only be performed under highly restrictive biocontainment conditions. We therefore characterized six antibody-detecting assays for their correlation with authentic virus neutralization. The significance of our research is in outlining the advantages and disadvantages of the different assays and identifying the optimal surrogate assay for authentic virus neutralization. This will allow for more accurate assessments of protective immunity against SARS-CoV-2 following infection and vaccination.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Neutralization Tests/methods , SARS-CoV-2/immunology , Adult , Enzyme-Linked Immunosorbent Assay/methods , Female , Humans , Male , Middle Aged , Protein Domains/immunology , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/immunology , Vesicular stomatitis Indiana virus/immunology , Vesicular stomatitis New Jersey virus/immunology
12.
Nat Commun ; 12(1): 6196, 2021 10 26.
Article in English | MEDLINE | ID: covidwho-1493097

ABSTRACT

As countries decide on vaccination strategies and how to ease movement restrictions, estimating the proportion of the population previously infected with SARS-CoV-2 is important for predicting the future burden of COVID-19. This proportion is usually estimated from serosurvey data in two steps: first the proportion above a threshold antibody level is calculated, then the crude estimate is adjusted using external estimates of sensitivity and specificity. A drawback of this approach is that the PCR-confirmed cases used to estimate the sensitivity of the threshold may not be representative of cases in the wider population-e.g., they may be more recently infected and more severely symptomatic. Mixture modelling offers an alternative approach that does not require external data from PCR-confirmed cases. Here we illustrate the bias in the standard threshold-based approach by comparing both approaches using data from several Kenyan serosurveys. We show that the mixture model analysis produces estimates of previous infection that are often substantially higher than the standard threshold analysis.


Subject(s)
Antibodies, Viral/blood , COVID-19/epidemiology , SARS-CoV-2/immunology , Bias , COVID-19/blood , COVID-19/immunology , COVID-19 Serological Testing , Humans , Kenya/epidemiology , Models, Statistical , SARS-CoV-2/isolation & purification , Sensitivity and Specificity , Seroepidemiologic Studies
15.
JAMA ; 326(14): 1400-1409, 2021 10 12.
Article in English | MEDLINE | ID: covidwho-1490612

ABSTRACT

Importance: People who have been infected with or vaccinated against SARS-CoV-2 have reduced risk of subsequent infection, but the proportion of people in the US with SARS-CoV-2 antibodies from infection or vaccination is uncertain. Objective: To estimate trends in SARS-CoV-2 seroprevalence related to infection and vaccination in the US population. Design, Setting, and Participants: In a repeated cross-sectional study conducted each month during July 2020 through May 2021, 17 blood collection organizations with blood donations from all 50 US states; Washington, DC; and Puerto Rico were organized into 66 study-specific regions, representing a catchment of 74% of the US population. For each study region, specimens from a median of approximately 2000 blood donors were selected and tested each month; a total of 1 594 363 specimens were initially selected and tested. The final date of blood donation collection was May 31, 2021. Exposure: Calendar time. Main Outcomes and Measures: Proportion of persons with detectable SARS-CoV-2 spike and nucleocapsid antibodies. Seroprevalence was weighted for demographic differences between the blood donor sample and general population. Infection-induced seroprevalence was defined as the prevalence of the population with both spike and nucleocapsid antibodies. Combined infection- and vaccination-induced seroprevalence was defined as the prevalence of the population with spike antibodies. The seroprevalence estimates were compared with cumulative COVID-19 case report incidence rates. Results: Among 1 443 519 specimens included, 733 052 (50.8%) were from women, 174 842 (12.1%) were from persons aged 16 to 29 years, 292 258 (20.2%) were from persons aged 65 years and older, 36 654 (2.5%) were from non-Hispanic Black persons, and 88 773 (6.1%) were from Hispanic persons. The overall infection-induced SARS-CoV-2 seroprevalence estimate increased from 3.5% (95% CI, 3.2%-3.8%) in July 2020 to 20.2% (95% CI, 19.9%-20.6%) in May 2021; the combined infection- and vaccination-induced seroprevalence estimate in May 2021 was 83.3% (95% CI, 82.9%-83.7%). By May 2021, 2.1 SARS-CoV-2 infections (95% CI, 2.0-2.1) per reported COVID-19 case were estimated to have occurred. Conclusions and Relevance: Based on a sample of blood donations in the US from July 2020 through May 2021, vaccine- and infection-induced SARS-CoV-2 seroprevalence increased over time and varied by age, race and ethnicity, and geographic region. Despite weighting to adjust for demographic differences, these findings from a national sample of blood donors may not be representative of the entire US population.


Subject(s)
Antibodies, Viral/blood , Blood Donors , COVID-19 Vaccines , COVID-19/epidemiology , SARS-CoV-2/immunology , Adolescent , Adult , Age Factors , Aged , COVID-19/ethnology , COVID-19 Serological Testing , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Prevalence , Seroepidemiologic Studies , United States/epidemiology , Young Adult
16.
J Gen Virol ; 102(10)2021 10.
Article in English | MEDLINE | ID: covidwho-1488154

ABSTRACT

A number of seroassays are available for SARS-CoV-2 testing; yet, head-to-head evaluations of different testing principles are limited, especially using raw values rather than categorical data. In addition, identifying correlates of protection is of utmost importance, and comparisons of available testing systems with functional assays, such as direct viral neutralisation, are needed.We analysed 6658 samples consisting of true-positives (n=193), true-negatives (n=1091), and specimens of unknown status (n=5374). For primary testing, we used Euroimmun-Anti-SARS-CoV-2-ELISA-IgA/IgG and Roche-Elecsys-Anti-SARS-CoV-2. Subsequently virus-neutralisation, GeneScriptcPass, VIRAMED-SARS-CoV-2-ViraChip, and Mikrogen-recomLine-SARS-CoV-2-IgG were applied for confirmatory testing. Statistical modelling generated optimised assay cut-off thresholds. Sensitivity of Euroimmun-anti-S1-IgA was 64.8%, specificity 93.3% (manufacturer's cut-off); for Euroimmun-anti-S1-IgG, sensitivity was 77.2/79.8% (manufacturer's/optimised cut-offs), specificity 98.0/97.8%; Roche-anti-N sensitivity was 85.5/88.6%, specificity 99.8/99.7%. In true-positives, mean and median Euroimmun-anti-S1-IgA and -IgG titres decreased 30/90 days after RT-PCR-positivity, Roche-anti-N titres decreased significantly later. Virus-neutralisation was 80.6% sensitive, 100.0% specific (≥1:5 dilution). Neutralisation surrogate tests (GeneScriptcPass, Mikrogen-recomLine-RBD) were >94.9% sensitive and >98.1% specific. Optimised cut-offs improved test performances of several tests. Confirmatory testing with virus-neutralisation might be complemented with GeneScriptcPassTM or recomLine-RBD for certain applications. Head-to-head comparisons given here aim to contribute to the refinement of testing strategies for individual and public health use.


Subject(s)
COVID-19 Serological Testing/methods , COVID-19/diagnosis , Neutralization Tests/methods , SARS-CoV-2/immunology , COVID-19 Nucleic Acid Testing , Cohort Studies , Humans
17.
Front Immunol ; 12: 753435, 2021.
Article in English | MEDLINE | ID: covidwho-1485058

ABSTRACT

Saliva is a body fluid with hitherto unused potential for the assessment of SARS-CoV-2 antibodies. Specific antibodies can indicate a past SARS-CoV-2 infection and allow to estimate the proportion of individuals with a potential protective immunity. First, we carefully characterized plasma samples obtained from adult control groups with and without prior SARS-CoV-2 infection using certified reference ELISAs. Simultaneously collected saliva samples of confirmed convalescent and negative individuals where then used to validate the herein newly developed ELISA for the detection of SARS-CoV-2 IgG antibodies in saliva. The saliva ELISA was applied to assess SARS-CoV-2 exposure in young children (N = 837) in the age between 1 and 10 years in Tübingen, Germany, towards the end of the first pandemic year 2020. Sensitivity and specificity of the new saliva ELISA was 87% and 100%, respectively. With 12% of all Tübingen children sampled via their respective educational institutions, estimates of SARS-CoV-2 antibody prevalence was 1.6%. Interestingly, only 0.4% preschool kids were positive compared to 3.0% of primary school children. Less than 20% of positive children self-reported symptoms within two months prior to saliva sampling that could be associated - but not exclusively - with a SARS-CoV-2 infection. The saliva ELISA is a valid and suitable protocol to enable population-based surveys for SARS-CoV-2 antibodies. Using non-invasive sampling and saliva ELISA testing, we found that prevalence of SARS-CoV-2 antibodies was significantly lower in young children than in primary school children.


Subject(s)
Antibodies, Viral/immunology , COVID-19 Serological Testing , COVID-19 , SARS-CoV-2/immunology , Saliva/immunology , Adult , COVID-19/diagnosis , COVID-19/immunology , Child , Child, Preschool , Enzyme-Linked Immunosorbent Assay , Female , Germany , Humans , Infant , Male , Prospective Studies
18.
Front Immunol ; 12: 693462, 2021.
Article in English | MEDLINE | ID: covidwho-1485053

ABSTRACT

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in December 2019 in Wuhan, China, and then rapidly spread causing an unprecedented pandemic. A robust serological assay is needed to evaluate vaccine candidates and better understand the epidemiology of coronavirus disease (COVID-19). Methods: We used the full-length spike (S) protein of SARS-CoV-2 for the development of qualitative and quantitative IgG and IgA anti-S enzyme linked immunosorbent assays (ELISA). A total of 320 sera used for assay development were comprised of pandemic sera from SARS-CoV-2 infected adults (n=51) and pre-pandemic sera (n=269) including sera from endemic human coronavirus infected adults. Reverse cumulative curves and diagnostic test statistics were evaluated to define the optimal serum dilution and OD cutoff value for IgG anti-S and IgA anti-S ELISAs. The IgG and IgA anti-S, and three functional antibodies (ACE-2 receptor blocking antibody, lentipseudovirus-S neutralizing antibody, and SARS-CoV-2 neutralizing antibody) were measured using additional SARS-CoV-2 PCR positive sera (n=76) and surveillance sera (n=25). Lastly, the IgG and IgA anti-S levels were compared in different demographic groups. Results: The optimal serum dilution for the qualitative IgG anti-S ELISA was at 1:1024 yielding a 99.6% specificity, 92.2% sensitivity, 92.9% positive predictive value (PPV), and 99.6% negative predictive value (NPV) at a SARS-CoV-2 seroprevalence of 5%. The optimal serum dilution for the qualitative IgA anti-S ELISA was at 1:128 yielding a 98.9% specificity, 76.5% sensitivity, 78.3% PPV, and 98.8% NPV at the same seroprevalence. Significant correlations were demonstrated between the IgG and IgA (r=0.833 for concentrations, r=0.840 for titers) as well as between IgG and three functional antibodies (r=0.811-0.924 for concentrations, r=0.795-0.917 for titers). The IgG and IgA anti-S levels were significantly higher in males than females (p<0.05), and in adults with moderate/severe symptoms than in adults with mild/moderate symptoms (p<0.001). Conclusion: We developed a highly specific and sensitive IgG anti-S ELISA assay to SARS-CoV-2 using full length S protein. The IgG anti-S antibody level was strongly associated with IgA and functional antibody levels in adults with SARS-CoV-2 infection. Gender and disease severity, rather than age, play an important role in antibody levels.


Subject(s)
Antibodies, Viral/immunology , COVID-19/immunology , Immunoglobulin A/immunology , Immunoglobulin G/immunology , SARS-CoV-2/immunology , Adult , COVID-19/diagnosis , COVID-19 Serological Testing , Female , HEK293 Cells , Humans
19.
PLoS One ; 16(10): e0259070, 2021.
Article in English | MEDLINE | ID: covidwho-1484863

ABSTRACT

Public health surveillance systems likely underestimate the true prevalence and incidence of SARS-CoV-2 infection due to limited access to testing and the high proportion of subclinical infections in community-based settings. This ongoing prospective, observational study aimed to generate accurate estimates of the prevalence and incidence of, and risk factors for, SARS-CoV-2 infection among residents of a central North Carolina county. From this cohort, we collected survey data and nasal swabs every two weeks and venous blood specimens every month. Nasal swabs were tested for the presence of SARS-CoV-2 virus (evidence of active infection), and serum specimens for SARS-CoV-2-specific antibodies (evidence of prior infection). As of June 23, 2021, we have enrolled a total of 153 participants from a county with an estimated 76,285 total residents. The anticipated study duration is at least 24 months, pending the evolution of the pandemic. Study data are being shared on a monthly basis with North Carolina state health authorities and future analyses aim to compare study data to state-wide metrics over time. Overall, the use of a probability-based sampling design and a well-characterized cohort will enable collection of critical data that can be used in planning and policy decisions for North Carolina and may be informative for other states with similar demographic characteristics.


Subject(s)
COVID-19 Nucleic Acid Testing/statistics & numerical data , COVID-19 Serological Testing/statistics & numerical data , COVID-19/epidemiology , Population Surveillance , Adult , COVID-19/diagnosis , COVID-19 Nucleic Acid Testing/methods , COVID-19 Serological Testing/methods , Cohort Studies , Demography/statistics & numerical data , Female , Humans , Male , North Carolina , Practice Guidelines as Topic , Risk
20.
Monoclon Antib Immunodiagn Immunother ; 40(5): 210-218, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1483363

ABSTRACT

The novel coronavirus disease (COVID-19), known as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), exhibits a strong human-to-human transmission infectivity and could cause acute respiratory infections. Therefore, simple and rapid serological testing is urgently needed to recognize positive cases. In this study, a point-of-care serological test based on lateral flow immunoassay (LFIA) was developed and its application for the simultaneous detection of IgM/IgG antibodies against SARS-CoV-2 was evaluated. The recombinant SARS-CoV-2 antigens were conjugated to the produced colloidal gold nanoparticles and used as the detection reagent. This test required only 10-15 minutes to achieve simultaneous qualitative detection of IgM/IgG antibodies specific to SARS-CoV-2 in 20 µL of serum or plasma samples. The clinical performance and reliability of the assay were evaluated by performing the test with 60 samples and comparing the results of these tests with those obtained via real-time polymerase chain reaction. The sensitivity and specificity of our assay were defined to be 90% and 96.6%, respectively. The presented LFIA was sufficiently sensitive and accurate to be used for the rapid diagnosis of coronavirus disease 2019 in laboratories or in patient care settings, particularly in emergency conditions, in which many samples require to be evaluated on time.


Subject(s)
Immunoassay/methods , Immunoglobulin G/blood , Immunoglobulin M/blood , Metal Nanoparticles/chemistry , SARS-CoV-2/immunology , Antibodies, Viral/blood , COVID-19 Serological Testing/methods , Colloids/chemistry , Cross Reactions , Gold , Humans , Immunoassay/instrumentation , Reagent Strips , Sensitivity and Specificity
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