Correlation Analysis of Anti-SARS-CoV-2 RBD IgG and Neutralizing Antibody against SARS-CoV-2 Omicron Variants after Vaccination

• Published in: Diagnostics (Basel) Vol. 12; no. 6; p. 1315
• Main Authors: Takheaw, Nuchjira, Liwsrisakun, Chalerm, Chaiwong, Warawut, Laopajon, Witida, Pata, Supansa, Inchai, Juthamas, Duangjit, Pilaiporn, Pothirat, Chaicharn, Bumroongkit, Chaiwat, Deesomchok, Athavudh, Theerakittikul, Theerakorn, Limsukon, Atikun, Tajarernmuang, Pattraporn, Niyatiwatchanchai, Nutchanok, Trongtrakul, Konlawij, Kasinrerk, Watchara
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 25.05.2022; MDPI
• Subjects: Antibodies; Antigens; Coronaviruses; Correlation analysis; COVID-19; COVID-19 vaccine; COVID-19 vaccines; Enzymes; Health aspects; Immune response; Immunoglobulin G; Immunological research; Measurement; Methods; Mutation; Omicron variant; Pandemics; Plasma; Proteins; SARS-CoV-2; Serodiagnosis; Severe acute respiratory syndrome coronavirus 2; Statistical analysis; variants of concern; Viral proteins; Thailand; United States > US
• ISSN: 2075-4418; 2075-4418
• DOI: 10.3390/diagnostics12061315

Various vaccines have been developed to control the COVID-19 pandemic, but the available vaccines were developed using ancestral SARS-CoV-2 wild-type (WT) strains. Commercial anti-SARS-CoV-2 receptor binding domain (RBD) antibody assays have been established and employed for validation of vaccine efficacy. However, these assays were developed before the SARS-CoV-2 variants of concern (VOCs) emerged. It is unclear whether anti-RBD IgG levels can predict immunity against VOCs. In this study, we determined the correlations between the levels of anti-RBD IgG and neutralizing antibodies (NAbs) against SARS-CoV-2 variants in vaccinated subjects. After vaccination, 100% of subjects showed an anti-RBD IgG response, whereas 82, 79, 30, 75, and 2% showed NAb responses against WT, Alpha, Beta, Delta, and Omicron variants, respectively. A high correlation was observed between anti-RBD IgG and NAbs against WT, Alpha, Beta, and Delta, but not so for the Omicron NAbs. Among subjects with high levels of anti-RBD IgG, 93, 93, 71, 93, and 0% of them had NAbs against WT, Alpha, Beta, Delta, and Omicron variants, respectively. These results indicate that anti-RBD IgG levels cannot be used as a predictor for the presence of NAbs against the globally dominant SARS-CoV-2 Omicron variant.