Antibody Response Induced by BNT162b2 and mRNA-1273 Vaccines against the SARS-CoV-2 in a Cohort of Healthcare Workers

Abstract

The aim of this study was to characterize the antibody response induced by SARS-CoV-2 mRNA vaccines in a cohort of healthcare workers. A total of 2247 serum samples were analyzed using the Elecsys® Anti-SARS-CoV-2 S-test (Roche Diagnostics International Ltd., Rotkreuz, Switzerland). Sex, age, body mass index (BMI), arterial hypertension, smoking and time between infection and/or vaccination and serology were considered the confounding factors. Regarding the medians, subjects previously infected with SARS-CoV-2 who preserved their response to the nucleocapsid (N) protein showed higher humoral immunogenicity (BNT162b2: 6456.0 U/mL median; mRNA-1273: 2505.0 U/mL) compared with non-infected (BNT162b2: 867.0 U/mL; mRNA-1273: 2300.5 U/mL) and infected subjects with a lost response to N protein (BNT162b2: 2992.0 U/mL). After controlling for the confounders, a higher response was still observed for mRNA-1273 compared with BNT162b2 in uninfected individuals (FC = 2.35, p < 0.0001) but not in previously infected subjects (1.11 FC, p = 0.1862). The lowest levels of antibodies were detected in previously infected non-vaccinated individuals (39.4 U/mL). Clinical variables previously linked to poor prognoses regarding SARS-CoV-2 infection, such as age, BMI and arterial hypertension, were positively associated with increasing levels of anti-S protein antibody exclusively in infected subjects. The mRNA-1273 vaccine generated a higher antibody response to the S protein than BNT162b2 in non-infected subjects only.

Keywords: BNT162b2; SARS-CoV-2; antibodies; mRNA-1273; vaccine.

Figure 1

Antibody response against SARS-CoV-2 spike protein in a cohort of healthcare workers (HCWs). Subjects were grouped according to their infection and conservation status of antibody response against the nucleocapsid protein. Boxplots represent the distribution of anti-spike protein antibody quantification. (a) Upper and lower bounds of boxes indicate the 75th and 25th percentiles, respectively. Whiskers extend 1.5 times the interquartile range (IQR) from each extreme of the box. Diamond-shape symbols represent the adjusted group means of anti-spike protein antibody titer after statistical control for confounders, and their extension represents their 95% confidence intervals. (b) Adjusted means and 95% confidence intervals of the anti-spike protein antibody titer after statistical control for confounders in the vaccinated subject groups. Estimations were derived from a linear mixed-effect model in which the sample’s donor was modeled as a random effect to account for intra-individual variability, and were adjusted by sex, age, BMI, arterial hypertension, smoking habit and time interval from infection and/or vaccination to serology. Anti-spike protein antibody quantifications are expressed in a log2-scale.