Abstract
Background: This study monitored total anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) RBD (receptor-binding domain) antibodies levels in a large population of healthcare workers undergoing mRNA COVID-19 vaccination. Methods. The study population consisted of employees of Pederzoli Hospital of Peschiera del Garda (Verona, Italy), who underwent voluntary vaccination with two doses of COVID-19 mRNA BNT162b2 (Comirnaty; Pfizer Inc). Venous blood was drawn immediately before the first vaccine dose, as well as 21 days (immediately before second vaccine dose) and 50 days afterwards. Humoral response was assessed with Roche Elecsys Anti-SARS-CoV-2 S total antibodies, on Roche Cobas 6000 (Roche Diagnostics). Results: The final study population consisted of 925 subjects (mean age, 44 ± 13 years; 457 women), 206 (22.3%) anti-SARS-CoV-2 baseline seropositive. The increase of total anti-SARS-CoV-2 RBD antibodies levels 21 days after the first vaccine dose was ~3 orders of magnitude higher in seropositive than in seronegative individuals (11782 vs. 42 U/mL; p < 0.001). Total anti-SARS-CoV-2 RBD antibodies levels further increased by over 30-fold after the second vaccine dose in baseline seronegative subjects, while such increase was only ~1.3-fold in baseline seropositive subjects. In multivariate analysis, total anti-SARS-CoV-2 RBD antibodies level was inversely associated with age after both vaccine doses and male sex after the second vaccine dose in baseline seronegative subjects, while baseline antibodies value significantly predicted immune response after both vaccine doses in baseline seropositive recipients. Conclusion: Significant difference exists in post-mRNA COVID-19 vaccine immune response in baseline seronegative and seropositive subjects, which seems dependent on age and sex in seronegative subjects, as well as on baseline anti-SARS-CoV-2 antibodies level in seropositive patients.
Highlights
The initial study population consisted of 1003 employees of the Pederzoli Hospital of Peschiera del Garda, who voluntarily agreed to undergo vaccination with Pfizer COVID19 mRNA Vaccine Comirnaty
BNT162b2 vaccine and failed to find significant differences between sexes, we found that women had a significantly higher response of total anti-SARS-CoV-2 receptor-binding domain (RBD) antibodies, especially after the second vaccine dose
Our findings are in substantial agreement with these previous observations, we provide further evidence that the baseline antibody status is a very strong predictor of post-vaccine total anti-SARS-CoV-2 RBD antibodies response, with high correlation after the first and second vaccine doses
Summary
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), generates a wide spectrum of clinical manifestations, from asymptomatic infection to severe lower respiratory tract involvement (with interstitial pneumonia), progressing toward severe systemic disease and development of multiple organ failure in patients with severe illness, up to death [2]. Owing to the nearly unstoppable worldwide diffusion of SARS-CoV-2, several preventative and containing measures have been adopted. Besides physical interventions, such as social distancing, widespread use of face masks, hand hygiene and timely isolation of infected and infectious subjects, universal vaccination is regarded as the most effective strategy to limit the clinical, societal and economic consequences of COVID-19 around the world [3]
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