Antibody Response to Symptomatic Infection With SARS-CoV-2 Omicron Variant Viruses, December 2021-June 2022.

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• SARS-CoV-2 Omicron variant caused widespread infection.
• Understanding humoral immune responses is crucial for managing COVID-19.
• Previous studies have focused on different variants or vaccination.

Purpose of the Study:

• To characterize humoral immune responses in patients infected with the SARS-CoV-2 Omicron variant.
• To quantify changes in binding antibody concentrations during acute infection and convalescence.
• To assess the utility of dried blood spots for evaluating immune responses.

Main Methods:

• Studied 105 ambulatory patients with laboratory-confirmed SARS-CoV-2 Omicron infection.
• Collected dried blood spot (DBS) samples during acute illness (within 5 days of onset) and convalescence.
• Measured binding antibody (bAb) levels against ancestral spike protein receptor binding domain (RBD) and nucleocapsid (N) protein using a commercial multiplex bead assay.

Main Results:

• Geometric mean bAb concentrations against RBD increased from 1258 to 3189 units/mL (2.5-fold increase).
• Geometric mean bAb concentrations against N protein increased from 5.5 to 259 units/mL (47-fold increase).
• Lower antibody concentrations were associated with greater geometric mean ratios, suggesting a robust response.

Conclusions:

• Humoral immune responses, particularly against the nucleocapsid protein, are significantly boosted following SARS-CoV-2 Omicron variant infection.
• Paired DBS specimens are a viable method for evaluating the humoral immune response to SARS-CoV-2 infection.
• Findings contribute to understanding immunity following Omicron variant infection.