Overview of Anti-SARS-CoV-2 Immune Response Six Months after BNT162b2 mRNA Vaccine.

Claudia Gandolfo,Chiara Terrosi,Monica Bocchia,Maria Grazia Cusi,Federico Franchi,Marco Mugnaini,Gabriele Anichini,Anna Sicuranza,Alessandro Gozzetti,Gianni Gori Savellini

doi:10.3390/vaccines10020171

Claudia Gandolfo, Chiara Terrosi + Show 8 more

Open Access

https://doi.org/10.3390/vaccines10020171

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Abstract

Background: We have designed a prospective study aiming to monitor the immune response in 178 health care workers six months after BNT162b2 mRNA vaccination. Methods: The humoral immune response of all subjects was evaluated by chemiluminescence (CMIA); in 60 serum samples, a live virus-based neutralization assay was also tested. Moreover, 6 months after vaccination, B- and T-cell subsets from 20 subjects were observed by FACS analysis after restimulation with the trimeric SARS-CoV-2 Spike protein as an antigen, thus mimicking reinfection in vitro. Results: A significant decrease of circulating IgG levels and neutralizing antibodies over time were observed. Moreover, six months after vaccination, a variable T-cell immune response after in vitro antigen stimulation of PBMC was observed. On the contrary, the analysis of B-cell response showed a shift from unswitched to switched memory B-cells and an increase of Th17 cells. Conclusions: Although the variability of the CD4+ and CD8+ immune response and an antibody decline was observed among vaccinated subjects, the increase of switched memory B-cells and Th17 cells, correlating with the presence of neutralizing antibodies, opened the debate on the correct timing of vaccination.

Highlights

We have designed a prospective study aiming to monitor the immune response in 178 health care workers six months after BNT162b2 messenger RNA (mRNA) vaccination
We analyzed sera from 178 healthcare workers, 61 males (34.2%; mean age 45.8 years, CI 95% 42.6–49.1) and 117 females (65.8%; mean age 44.4 years, CI 95% 42.1–46.6) who had never been infected by SARS-CoV-2 10 days, one month, three months, and six months after the second dose of BNT162b2 mRNA vaccine (Figure 1)
There are several articles in the scientific literature regarding the immunity after SARS-CoV-2 natural infection [15,16,17,18,19] and on the duration of the immune response after vaccination [4,9,10,20,21]

Summary

Introduction

We have designed a prospective study aiming to monitor the immune response in 178 health care workers six months after BNT162b2 mRNA vaccination. 6 months after vaccination, B- and T-cell subsets from 20 subjects were observed by FACS analysis after restimulation with the trimeric SARS-CoV-2 Spike protein as an antigen, mimicking reinfection in vitro. Six months after vaccination, a variable T-cell immune response after in vitro antigen stimulation of PBMC was observed. The analysis of B-cell response showed a shift from unswitched to switched memory B-cells and an increase of Th17 cells. Conclusions: the variability of the CD4+ and CD8+ immune response and an antibody decline was observed among vaccinated subjects, the increase of switched memory B-cells and Th17 cells, correlating with the presence of neutralizing antibodies, opened the debate on the correct timing of vaccination

Methods

Results

Conclusion