BNT162b2 mRNA SARS-CoV-2 Vaccine Elicits High Avidity and Neutralizing Antibodies in Healthcare Workers.

Federico Pratesi,Teresita Caruso,Tiziano Tarpanelli,Alessandra Gentili,Paola Migliorini,Davide Gioè,Davide Testa

doi:10.3390/vaccines9060672

Abstract

The BNT162b2 vaccine, containing lipid nanoparticles-formulated mRNA encoding the full-length spike protein of SARS-CoV-2, has been employed to immunize health care workers in Italy, administered in two doses 21 days apart. In this study, we characterized the antibody response induced by the BNT162b2 vaccine in a group of health care workers, tested at baseline, after the first dose and after the booster. Thirty-nine subjects without previous exposure to SARS-CoV-2 were vaccinated with the BNT162b2 vaccine. IgM, IgG, and IgA anti-receptor binding domain (RBD) were tested by ELISA. Neutralizing antibodies were evaluated testing the inhibition of RBD binding to ACE2. Antibody avidity was measured by urea avidity ELISA. IgM anti-RBD are produced after the first dose of vaccine and persist after the booster. IgG and IgA anti-RBD antibodies are detected in high amounts in all the subjects after the first dose and further increase after the booster. A few subjects, already after the first dose, produce antibodies inhibiting RBD interaction with ACE2. After the booster, high levels of inhibitory antibodies are detected in all the subjects. Affinity maturation takes place with boosting and IgG anti-RBD avidity increases with the number of immunizations. A less pronounced increase is observed with IgA. These data indicate that the BNT162b2 vaccine can induce high levels of protective antibodies of high avidity in vaccinated subjects; both IgG and IgA anti-RBD antibodies are produced. Further studies are needed to evaluate antibody persistence over time.

Highlights

Sera obtained from 17 patients recovered in intensive care units with positive SARS-CoV-2 PCR nasopharyngeal swab and clinical symptoms of COVID-19 were used as the control for IgG avidity assay
Antibody levels obtained by this test highly correlate with commercial anti-receptor binding domain (RBD) assays (Spearman rank coefficient = 0.9349; p < 0.0001—Supplementary Figure S1)
The data we obtained confirm that the BNT162b2 vaccine is highly effective in inducing both IgG and IgA anti-RBD antibodies, which are produced after the first dose and further increase after the second one

Summary

Introduction

The COVID-19 pandemic outbreak, caused by the novel severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2), emerged at the end of 2019 in Wuhan, China and rapidly spread all around the world, still representing a threat for the public health.Social distancing, partial or total lockdowns, and public education about personal protection have been exploited by all countries and helped to limit the virus’ transmission and to relieve the burden on hospital wards, but were far from representing a solution for the challenge launched by SARS-CoV-2.The best strategy to fight the pandemic is represented by a global vaccination campaign able to administer safe and effective vaccines for the protection of individuals, to achieve sufficient herd immunity to control the COVID-19 pandemic [1].Facing such a challenge, SARS-CoV-2 vaccines have been developed at a very rapid pace thanks to the previous knowledge on the role of spike protein in SARS infection, the availability of the SARS-CoV-2 genetic structure and the evolution of nucleic acid vaccine technology platforms.The extraordinary efforts made by every country during the COVID-19 pandemic, together with development activities run in parallel and not sequentially, allowed this goal to be achieved in a remarkably short time.mRNA platform technology has allowed the rapid manufacturing of SARS-CoV-2 vaccines, and currently, two of them (BNT162b2 and mRNA-1273) have been validated for emergency use all over the world [2,3,4]. The best strategy to fight the pandemic is represented by a global vaccination campaign able to administer safe and effective vaccines for the protection of individuals, to achieve sufficient herd immunity to control the COVID-19 pandemic [1]. Facing such a challenge, SARS-CoV-2 vaccines have been developed at a very rapid pace thanks to the previous knowledge on the role of spike protein in SARS infection, the availability of the SARS-CoV-2 genetic structure and the evolution of nucleic acid vaccine technology platforms. BNT162b2 ( known as Comirnaty or tozinameran) has been employed to immunize health care workers in Italy, administered in two doses 21 days apart

Methods

Results

Conclusion