Analytic comparison between three high-throughput commercial SARS-CoV-2 antibody assays reveals minor discrepancies in a high-incidence population

• Published in: Scientific reports 2021-06, Vol.11 (1), p.11837-10, Article 11837
• Main Authors: Nasrallah, Gheyath K., Dargham, Soha R., Shurrab, Farah, Al-Sadeq, Duaa W., Al-Jighefee, Hadeel, Chemaitelly, Hiam, Al Kanaani, Zaina, Al Khal, Abdullatif, Al Kuwari, Einas, Coyle, Peter, Jeremijenko, Andrew, Kaleeckal, Anvar Hassan, Latif, Ali Nizar, Shaik, Riyazuddin Mohammad, Rahim, Hanan F. Abdul, Yassine, Hadi M., Al Kuwari, Mohamed G., Qotba, Hamda, Al Romaihi, Hamad Eid, Tang, Patrick, Bertollini, Roberto, Al-Thani, Mohamed H., Althani, Asmaa A., Abu-Raddad, Laith J.
• Format: Article
• Language: English
• Subjects: 692/308/174; 692/699/255; 692/699/255/2514; Antibodies; Antibodies, Viral - immunology; COVID-19; COVID-19 - diagnosis; COVID-19 - epidemiology; COVID-19 - immunology; COVID-19 Serological Testing - economics; COVID-19 Serological Testing - methods; Humanities and Social Sciences; Humans; Immunoglobulin G; Immunoglobulin G - immunology; Incidence; Infections; multidisciplinary; SARS-CoV-2 - immunology; SARS-CoV-2 - isolation & purification; Science; Science (multidisciplinary); Sensitivity and Specificity; Serology; Severe acute respiratory syndrome coronavirus 2
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-91235-x

Performance of three automated commercial serological IgG-based assays was investigated for assessing SARS-CoV-2 “ever” (past or current) infection in a population-based sample in a high exposure setting. PCR and serological testing was performed on 394 individuals. SARS-CoV-2-IgG seroprevalence was 42.9% (95% CI 38.1–47.8%), 40.6% (95% CI 35.9–45.5%), and 42.4% (95% CI 37.6–47.3%) using the CL-900i, VidasIII, and Elecsys assays, respectively. Between the three assays, overall, positive, and negative percent agreements ranged between 93.2–95.7%, 89.3–92.8%, and 93.8–97.8%, respectively; Cohen’s kappa statistic ranged from 0.86 to 0.91; and 35 specimens (8.9%) showed discordant results. Among all individuals, 12.5% (95% CI 9.6–16.1%) had current infection, as assessed by PCR. Of these, only 34.7% (95% CI 22.9–48.7%) were seropositive by at least one assay. A total of 216 individuals (54.8%; 95% CI 49.9–59.7%) had evidence of ever infection using antibody testing and/or PCR during or prior to this study. Of these, only 78.2%, 74.1%, and 77.3% were seropositive in the CL-900i, VidasIII, and Elecsys assays, respectively. All three assays had comparable performance and excellent agreement, but missed at least 20% of individuals with past or current infection. Commercial antibody assays can substantially underestimate ever infection, more so when infection rates are high.