Evaluation of pre-Omicron population immunity for SARS-CoV-2 in the Household Influenza Vaccine Evaluation (HIVE) cohort

BackgroundContinued serosurvey for SARS-CoV-2 population immunity is critical for vaccine strain selection and identification of susceptible groups such as young children. We aim to evaluate the use of a high-throughput, low-volume assay to describe strain-specific IgG measurement in a longitudinally followed community-based cohort. MethodsThe longitudinal Household Influenza Vaccine Evaluation study has observed around 300 households annually for acute respiratory illness. SARS-CoV-2 variant-specific IgG (including original, delta, beta, and omicron variants) concentrations were measured using multiplex electrochemiluminescence (ECL), pseudoviral neutralization (PN), and ACE2 inhibition assays in participants who had serum samples drawn between July 1 and December 31, 2021. Spearmans rank correlation coefficient assessed correlation within and between ECL, ACE2, and PN assays. Receiver operating characteristic (ROC) analysis evaluated the performance of ECL and ACE2 assays. Generalized Additive Mixed Models estimated population immunity by age against SARS-CoV-2 variants. ResultsA total of 156 serum samples from 117 participants were selected for this study. Most were from adults and a majority received vaccination during the analysis period. High correlations were observed within ECL (0.99-1.0), ACE2 (0.87-0.99), and between panels: ECL vs. PN (0.95-1.00), ACE2 vs. PN (0.85-0.96). ROC analysis showed medium to high areas under the curve, sensitivity, and specificity for ECL (0.85-0.87; 0.89-0.90; 0.87-0.88) and ACE2 (0.85-0.96; 0.94-1.0; 0.42-0.92). SARS-CoV-2 IgG concentrations are higher in older individuals, plateauing at age 20. ConclusionWe found a high correlation between ECL, ACE2, and PN across variants. Age-specific IgG quantities reflected behavior and infection histories collected by active surveillance.