Twelve-Month Follow-up of Early COVID-19 Cases in the United States: Cellular and Humoral Immune Longevity

Abstract

We quantify antibody and memory B-cell responses to severe acute respiratory syndrome coronavirus 2 at 6 and 12 months postinfection among 7 unvaccinated US coronavirus disease 2019 cases. All had detectable S-specific memory B cells and immunoglobulin G at both time points, with geometric mean titers of 117.2 BAU/mL and 84.0 BAU/mL at 6 and 12 months, respectively.

Keywords: COVID-19; SARS-CoV-2 infection; immunity; memory B cells.

Figure 1.

S-, RBD-, and N-specific IgG responses up to 12 months after COVID-19 illness onset among early US COVID-19 cases. Asterisks indicate that the patient received supplemental oxygen during their acute COVID-19 illness. Dashed lines indicate the threshold of detection for each assay. Spike-specific IgG titers from the acute time points (<45 days) and 6-month time points were previously published using a different assay [7]; specimens were retested using the V-PLEX SARS-CoV-2 Panel 2 Kit (Meso Scale Discovery) assay for standardized comparisons in this analysis. Abbreviations: COVID-19, coronavirus disease 2019; IgG, immunoglobulin G; N, nucleocapsid; RBD, receptor binding domain; S, spike.

Figure 2.

Percentage of S-specific IgG and IgA memory B cells at 6 and 12 months post–illness onset among early US COVID-19 cases. The percentage of S-specific memory B cells among all memory B cells is depicted. Asterisks indicate that the patient received supplemental oxygen during their acute COVID-19 illness. Participant K had no detectable IgA memory B cells at 189 days post–illness onset, and participant N had no detectable IgA memory B cells at 351 days. Abbreviations: COVID-19, coronavirus disease 2019; IgA, immunoglobulin A; IgG, immunoglobulin G; S, spike.