False-positive results of SARS-CoV-2 IgM/IgG antibody tests in sera stored before the 2020 pandemic in Italy

Tavano, Francesca; Panza, Anna; Palmieri, Orazio; Niro, G.A.; Andriulli, Nicola; Latiano, Tiziana; Corritore, Giuseppe; Gioffreda, Domenica; Gentile, Annamaria; Fontana, R.; Guerra, Maritza Linares; Biscaglia, Giuseppe; Bossa, Fabrizio; Carella, Massimo; Miscio, Giuseppe; Mauro, Lazzaro Di

doi:10.1016/j.ijid.2020.12.067

Cited by 27 publications

(35 citation statements)

References 16 publications

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“…These unspecific positive signals might not only give false indication of protective immunity to SARS-CoV-2 for an individual with RF but might also give an incorrect picture of the proportion of the population exposed to the infection during larger screenings, especially if the diagnoses or RF status of the population from where samples were collected are unknown. Most of the false positive signals were detected in the IgM assays, as has been noted by others (16,34), which might be in line with the broader low affinity quality of the IgM antibodies, as compared to IgG class switched and affinity matured antibodies. Other studies have reported about this issue with different interpretations.…”

Section: Discussionsupporting

confidence: 80%

False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

et al. 2021

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Patients with chronic inflammatory diseases are often treated with immunosuppressants and therefore are of particular concern during the SARS-CoV-2 pandemic. Serological tests will improve our understanding of the infection and immunity in this population, unless they tests give false positive results. The aim of this study was to evaluate the specificity of SARS-Cov-2 serological assays using samples from patients with chronic inflammatory diseases collected prior to April 2019, thus defined as negative. Samples from patients with multiple sclerosis (MS, n=10), rheumatoid arthritis (RA, n=47) with or without rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (anti-CCP2) and systemic lupus erythematosus (SLE, n=10) with or without RF, were analyzed for SARS-CoV-2 antibodies using 17 commercially available lateral flow assays (LFA), two ELISA kits and one in-house developed IgG multiplex bead-based assay. Six LFA and the in-house validated IgG assay correctly produced negative results for all samples. However, the majority of assays (n=13), gave false positive signal for samples from patients with RA and SLE. This was most notable in samples from RF positive RA patients. No false positive samples were detected in any assay using samples from patients with MS. Poor specificity of commercial serological assays could possibly be, at least partly, due to interfering antibodies in samples from patients with chronic inflammatory diseases. For these patients, the risk of false positivity should be considered when interpreting results of the SARS-CoV-2 serological assays.

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Section: Discussionsupporting

confidence: 80%

False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

et al. 2021

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“…Smoking and stress or mental health disorder were inversely correlated with seropositivity; however, the latter should be interpreted with caution, as it is likely related to other non-recorded factors associated with smoking that may be the cause of this apparent protection, for example socializing outside. Importantly, smoking has been clearly associated with more severe disease [29] . We can speculate several reasons as to why stress and mental health disorders were protective, such as temporary leave from clinical activities, but this would have to be confirmed.…”

Section: Discussionmentioning

confidence: 99%

A cross sectional study found differential risks for COVID-19 seropositivity amongst health care professionals in Chile

Zuñiga

Lagomarcino

Muñoz

et al. 2022

Journal of Clinical Epidemiology

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Objective Healthcare workers (HCWs) are at increased risk for SARS-CoV-2 infection, however not all face the same risk. We aimed to determine IgG/IgM prevalence and risk factors associated with seropositivity in Chilean HCWs. Study Design and Setting This was a nationwide, cross-sectional study including a questionnaire and COVID-19 lateral flow IgG/IgM antibody testing. All HCWs in the Chilean public health care system were invited to participate following the country's first wave. Results IgG/IgM positivity in 85,529 HCWs was 7.2%, ranging from 1.6% to 12.4% between regions. Additionally, 9.7% HCWs reported a positive PCR of which 47% were seropositive. Overall, 10,863 (12.7%) HCWs were PCR and/or IgG/IgM positive.Factors independently associated with increased odds ratios (ORs) for seropositivity were: working in a hospital, night shifts, contact with Covid-19, using public transport, male gender, age>45, BMI ≥30, and reporting ≥2 symptoms. Stress/mental health disorder and smoking were associated with decreased ORs. These factors remained significant when including PCR positive cases in the model. Conclusions HCWs in the hospital were at highest risk for COVID-19, and several independent risk factors for seropositivity and/or PCR positivity were identified.

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“…The positive rates of the single SARS-CoV-2 IgM, single SARS-CoV-2 IgG, and SARS-CoV-2 IgM and IgG positive results among COVID-19 patients were 1.72%, 3.45%, and 94.83%, respectively, concluding that the combined detection of IgM and IgG had better practicability and sensitivity than IgM or IgG alone 31 . Interestingly, most false-positive signals were detected in the SARS-CoV-2 IgM assays, which other studies have also noted 28,32 . Thus, the combined detection of SARS-CoV-2 IgM and IgG should be given high priority in its implementation as the standard serological test in clinical and public health practice during the pandemic.…”

Section: Discussionmentioning

confidence: 53%

Distribution characteristics of SARS-CoV-2 IgM and IgG in false-positive results detected by Chemiluminescent immunoassay

Liang

Mou

et al. 2021

Preprint

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There have been several false-positive results in the antibody detection of the COVID-19. This study aims to analyze the distribution characteristics of SARS-CoV-2 IgM and IgG in false-positive results detected using chemiluminescent immunoassay. The characteristics of the false-positive results in SARS-CoV-2 IgM and IgG testing were retrospectively analyzed. The dynamic changes in the results of SARS-CoV-2 IgM and IgG antibodies were observed. The false-positive proportion of the single SARS-CoV-2 IgM positive results was 95.88%, which was significantly higher than those of the single SARS-CoV-2 IgG positive results (67.50%) (P < 0.001) and SARS-CoV-2 IgM & IgG positive results (29.55%) (P < 0.001). The S/CO of the SARS-CoV-2 IgM and IgG in false-positive results ranged from 1.0 to 50.0. The false-positive probability of SARS-CoV-2 IgM in the S/CO range (1.0 ~ 3.0) was 91.73% (77/84), and the probability of false-positive of SARS-CoV-2 IgG in the S/CO range (1.0 ~ 2.0) was 85.71% (24/28). Dynamic monitoring showed that the S/CO values of IgM in false-positive results decreased or remained unchanged, whereas the S/CO values of IgG in false-positive results only decreased. The possibility of false-positive of the single SARS-CoV-2 IgM positive and single SARS-CoV-2 IgG positive results was high. As the value of S/CO decreased, the probability of false-positive consequently increased, especially among the single SARS-CoV-2 IgM positive results.

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False-positive results of SARS-CoV-2 IgM/IgG antibody tests in sera stored before the 2020 pandemic in Italy

Cited by 27 publications

References 16 publications

False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

A cross sectional study found differential risks for COVID-19 seropositivity amongst health care professionals in Chile

Distribution characteristics of SARS-CoV-2 IgM and IgG in false-positive results detected by Chemiluminescent immunoassay

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