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1.
Clin Transl Immunology ; 10(7): e1312, 2021.
Article in English | MEDLINE | ID: covidwho-1321684

ABSTRACT

OBJECTIVE: The COVID-19 pandemic poses an immense need for accurate, sensitive and high-throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high-throughput multiplex bead-based serological assay. METHODS: More than 100 representations of SARS-CoV-2 proteins were included for initial evaluation, including antigens produced in bacterial and mammalian hosts as well as synthetic peptides. The five best-performing antigens, three representing the spike glycoprotein and two representing the nucleocapsid protein, were further evaluated for detection of IgG antibodies in samples from 331 COVID-19 patients and convalescents, and in 2090 negative controls sampled before 2020. RESULTS: Three antigens were finally selected, represented by a soluble trimeric form and the S1-domain of the spike glycoprotein as well as by the C-terminal domain of the nucleocapsid. The sensitivity for these three antigens individually was found to be 99.7%, 99.1% and 99.7%, and the specificity was found to be 98.1%, 98.7% and 95.7%. The best assay performance was although achieved when utilising two antigens in combination, enabling a sensitivity of up to 99.7% combined with a specificity of 100%. Requiring any two of the three antigens resulted in a sensitivity of 99.7% and a specificity of 99.4%. CONCLUSION: These observations demonstrate that a serological test based on a combination of several SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.

2.
J Infect Dis ; 224(1): 14-20, 2021 07 02.
Article in English | MEDLINE | ID: covidwho-1294728

ABSTRACT

BACKGROUND: Whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positivity among asymptomatic subjects reflects past or future disease may be difficult to ascertain. METHODS: We tested 9449 employees at Karolinska University Hospital, Stockholm, Sweden for SARS-CoV-2 RNA and antibodies, linked the results to sick leave records, and determined associations with past or future sick leave using multinomial logistic regression. RESULTS: Subjects with high amounts of SARS-CoV-2 virus, indicated by polymerase chain reaction (PCR) cycle threshold (Ct) value, had the highest risk for sick leave in the 2 weeks after testing (odds ratio [OR], 11.97; 95% confidence interval [CI], 6.29-22.80) whereas subjects with low amounts of virus had the highest risk for sick leave in the 3 weeks before testing (OR, 6.31; 95% CI, 4.38-9.08). Only 2.5% of employees were SARS-CoV-2 positive while 10.5% were positive by serology and 1.2% were positive in both tests. Serology-positive subjects were not at excess risk for future sick leave (OR, 1.06; 95% CI, .71-1.57). CONCLUSIONS: High amounts of SARS-CoV-2 virus, as determined using PCR Ct values, was associated with development of sickness in the next few weeks. Results support the concept that PCR Ct may be informative when testing for SARS-CoV-2. Clinical Trials Registration. NCT04411576.


Subject(s)
Asymptomatic Diseases , COVID-19/epidemiology , COVID-19/virology , Health Personnel , SARS-CoV-2 , Adult , Aged , Antibodies, Viral , COVID-19/diagnosis , Disease Progression , Female , Hospitals, University , Humans , Male , Mass Screening , Middle Aged , Polymerase Chain Reaction , RNA, Viral , SARS-CoV-2/genetics , Serologic Tests , Sick Leave/statistics & numerical data , Sweden/epidemiology , Young Adult
3.
Sci Rep ; 11(1): 5160, 2021 03 04.
Article in English | MEDLINE | ID: covidwho-1117661

ABSTRACT

The extent that antibodies to SARS-CoV-2 may protect against future virus-associated disease is unknown. We invited all employees (n = 15,300) at work at the Karolinska University Hospital, Stockholm, Sweden to participate in a study examining SARS-Cov-2 antibodies in relation to registered sick leave. For consenting 12,928 healthy hospital employees antibodies to SARS-CoV-2 could be determined and compared to participant sick leave records. Subjects with viral serum antibodies were not at excess risk for future sick leave (adjusted odds ratio (OR) controlling for age and sex: 0.85 [95% confidence interval (CI) (0.85 (0.43-1.68)]. By contrast, subjects with antibodies had an excess risk for sick leave in the weeks prior to testing [adjusted OR in multivariate analysis: 3.34 (2.98-3.74)]. Thus, presence of viral antibodies marks past disease and protection against excess risk of future disease. Knowledge of whether exposed subjects have had disease in the past or are at risk for future disease is essential for planning of control measures.Trial registration: First registered on 02/06/20, ClinicalTrials.gov NCT04411576.


Subject(s)
Antibodies, Viral/blood , COVID-19/immunology , SARS-CoV-2/immunology , Sick Leave/statistics & numerical data , Adult , Antibodies, Viral/immunology , COVID-19/epidemiology , Female , Follow-Up Studies , Humans , Male , Middle Aged , Sweden/epidemiology
4.
Nat Commun ; 11(1): 5064, 2020 10 08.
Article in English | MEDLINE | ID: covidwho-841875

ABSTRACT

SARS-CoV-2 may pose an occupational health risk to healthcare workers. Here, we report the seroprevalence of SARS-CoV-2 antibodies, self-reported symptoms and occupational exposure to SARS-CoV-2 among healthcare workers at a large acute care hospital in Sweden. The seroprevalence of IgG antibodies against SARS-CoV-2 was 19.1% among the 2149 healthcare workers recruited between April 14th and May 8th 2020, which was higher than the reported regional seroprevalence during the same time period. Symptoms associated with seroprevalence were anosmia (odds ratio (OR) 28.4, 95% CI 20.6-39.5) and ageusia (OR 19.2, 95% CI 14.3-26.1). Seroprevalence was also associated with patient contact (OR 2.9, 95% CI 1.9-4.5) and covid-19 patient contact (OR 3.3, 95% CI 2.2-5.3). These findings imply an occupational risk for SARS-CoV-2 infection among healthcare workers. Continued measures are warranted to assure healthcare workers safety and reduce transmission from healthcare workers to patients and to the community.


Subject(s)
Coronavirus Infections/epidemiology , Coronavirus Infections/etiology , Health Personnel/statistics & numerical data , Occupational Exposure/adverse effects , Pneumonia, Viral/epidemiology , Pneumonia, Viral/etiology , Adult , Antibodies, Viral/blood , Betacoronavirus/immunology , COVID-19 , Coronavirus Infections/pathology , Coronavirus Infections/transmission , Cross-Sectional Studies , Female , Hospitals , Humans , Immunoglobulin G/blood , Infectious Disease Transmission, Patient-to-Professional , Male , Middle Aged , Occupational Exposure/statistics & numerical data , Occupational Health , Pandemics , Pneumonia, Viral/pathology , Pneumonia, Viral/transmission , SARS-CoV-2 , Seroepidemiologic Studies , Sweden/epidemiology
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