Publication date: May 22, 2025
Higher circulating SARS-CoV-2 IgG titers correlate with SARS-CoV-2 ex vivo viral neutralization, but how well this translates to clinical protection in the real-world setting is unclear. In a prospective cohort study, we enrolled 44 SARS-CoV-2 negative, confirmed SARS-CoV-2 close contacts. Receptor-binding domain (RBD) and full-spike IgG and SARS-CoV-2 memory B-cell frequencies were measured at exposure, and participants were serially tested for incident infection over 14 days. Those who developed SARS-CoV-2 infection had significantly lower RBD titers, but not memory B-cell frequencies. An RBD IgG titer >6321 BAU/ml was associated with a reduced SARS-CoV-2 acquisition risk (HR 0. 32, 95% CI 0. 13-0. 81), while an RBD IgG titer >456 BAU/ml was associated with a reduced moderate or severe COVID-19 risk (HR 0. 15, 95% CI 0. 03-0. 81), identifying this threshold as a correlate of protection.
| Concepts | Keywords |
|---|---|
| 14days | antibodies |
| Immunol | B cells |
| Reduced | COVID-19 |
| Viral | SARS-CoV-2 |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | infection |
| disease | IDO | cell |
| disease | MESH | SARS-CoV-2 infection |
| pathway | REACTOME | SARS-CoV-2 Infection |