Correlation Analysis of Anti-SARS-CoV-2 RBD IgG and Neutralizing Antibody against SARS-CoV-2 Omicron Variants after Vaccination
Nuchjira Takheaw,
Chalerm Liwsrisakun,
Warawut Chaiwong,
Witida Laopajon,
Supansa Pata,
Juthamas Inchai,
Pilaiporn Duangjit,
Chaicharn Pothirat,
Chaiwat Bumroongkit,
Athavudh Deesomchok,
Theerakorn Theerakittikul,
Atikun Limsukon,
Pattraporn Tajarernmuang,
Nutchanok Niyatiwatchanchai,
Konlawij Trongtrakul,
Watchara Kasinrerk
Affiliations
Nuchjira Takheaw
Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
Chalerm Liwsrisakun
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Warawut Chaiwong
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Witida Laopajon
Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
Supansa Pata
Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
Juthamas Inchai
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Pilaiporn Duangjit
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Chaicharn Pothirat
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Chaiwat Bumroongkit
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Athavudh Deesomchok
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Theerakorn Theerakittikul
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Atikun Limsukon
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Pattraporn Tajarernmuang
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Nutchanok Niyatiwatchanchai
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Konlawij Trongtrakul
Division of Pulmonary, Critical Care, and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
Watchara Kasinrerk
Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
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.
