Impact of Previous Coronavirus Disease 2019 on Immune Response After a Single Dose of BNT162b2 Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine

Abstract

Immune response after a single dose of BNT162b2 vaccine was markedly increased in subjects with previous severe acute respiratory syndrome coronavirus 2 infection, reaching similar immunoglobulin titers to those elicited by the full 2 doses in naive cases, and increased modestly after the second dose. These data may inform the priority of the boosting dose.

Keywords: COVID-19; SARS-CoV-2; health care workers; immune response; vaccine.

Figure 1.

Serological response after 1 or 2 doses of the BNT162b2 messenger RNA coronavirus disease 2019 (COVID-19) vaccine in 641 health care workers. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G anti-spike (IgG-S) were determined 3 weeks after the first dose (light blue dots; n = 641) and 3 weeks after the second dose (dark blue dots; n = 623) with chemiluminescent immunoanalysis (Architect, ABBOTT Diagnostics) with a cutoff of <50 arbitrary units (AU)/mL. IgG-S titers are represented in a logarithmic scale (y-axis). Individual data (dots) and median values and interquartile range (boxes) of different groups (x-axis) are depicted. Statistics: univariate nonparametric test, Mann-Whitney U test, and Kruskal-Wallis test were used, as appropriate, to compare IgG-S titers between groups. Multiple comparisons were adjusted by the Bonferroni method. A, IgG-S titers in individuals who were SARS-CoV-2 naive or with previously documented infection. Of note, the strong serologic response in previously infected individuals after the first dose was of similar magnitude to that elicited by the 2-dose vaccine protocol in naive subjects. B, IgG-S titers in individuals according to their serologic SARS-CoV-2 status before vaccination. Seronegative: seronegative in both surveys. Transient seropositivity: seropositive in first survey and negative in second survey. Persistent seropositivity: seropositive in both surveys. Of note, the strong serologic response in infected individuals with persistent seropositivity after the first dose was even higher than that elicited by the 2-dose vaccine protocol in naive and transient seropositive patients (P < .001 for both comparisons); the response to the first dose of the vaccine in transient seropositive subjects was intermediate between seronegative subjects and persistent seropositive subjects. Boost effect was inversely related to the strength of the response to the first dose (P < .001; Supplementary Table 3). C, IgG-S titers in SARS-CoV-2–infected individuals according to their clinical COVID-19 presentation. Of note, the strong serologic response in subjects with previous SARS-CoV-2 infection after the first dose was even higher than that elicited by the 2-dose vaccine protocol in SARS-CoV-2–naive patients and increased progressively with the severity of the disease (P < .001). Boost effect was inversely related to the strength of the response to the first dose (P < .001; Supplementary Table 3).