Significant Increase of Antibody Titers After the 3rd Booster Dose of the Pfizer–BioNTech mRNA COVID-19 Vaccine in Healthcare Workers in Greece

11 Pages Posted: 4 Jan 2022

See all articles by Konstantina Kontopoulou

Konstantina Kontopoulou

G. Gennimatas General Hospital

Christos Nakas

University of Bern - University Institute of Clinical Chemistry; University of Thessaly

Georgios Papazisis

Aristotle University of Thessaloniki - Department of Clinical Pharmacology; Clinical Trials Unit, Special Unit for Biomedical Research and Education, School of Medicine, Aristotle University

Date Written: December 19, 2021

Abstract

Background: Aim of our study was to assess the immunogenicity of a third dose of the Pfizer–BioNTech mRNA COVID-19 vaccine (Comirnaty), in a cohort of health-care workers in Greece. Results on the immunogenicity of this vaccine in different time points after the 1st and the 2nd dose in this cohort have been already published by our group

Methods: Our study comprised of 129 participants whose anti-RBD IgG titers were monitored through the course of nine months. Antibody titers were obtained for each participant just before the third vaccine dose (nine months after the second dose), and one month after the third dose. Of the 129 participants in this study, 19 had been infected and recuperated from COVID-19 infection before the first vaccine dose.

We employed theSARS-CoV-2 IgG II Quant assay on the Architect System to longitudinally assess titers of neutralising IgG against the receptor-binding domain of the S1 subunit of the spike protein in participant-derived serum samples.

Results: The overall IgG GMC at nine months compared to its 6-month value were reduced by approximately 50% (fold change = 0.489). Boosters raised GMCs by a factor of approximately 23 relative to levels at 6 months (fold change = 22.8) and by a factor of approximately 47 relative to levels at 9 months (fold change = 46.3).

There were non-significant differences between females and males (p=0.893) nor between age groups (p=0.294) as opposed to the differences noted in all our previous measurements.
No significant difference between the two groups (prior/no prior COVID infection) were also found, with respect to the restriction of the upper limit of quantification at 40000 Au/ml and the high number of subjects reaching this.

Finally, it is of notice that the immune response after the third dose was significantly higher than the response achieved after the second dose (p=0.008).

Conclusion: A third dose of the Pfizer–BioNTech mRNA COVID-19 vaccine in health-care workers in Greece administered 9 months after the second dose causes a remarkable increase in the concentration of neutralising antibodies against SARS-CoV-2. Our findings verify the potent immunogenicity elicited by the 3rd dose in all age groups and prior or not prior infected subjects, suggesting that timely administration of the 3rd (booster)-dose maximizes the immunogenic potential of the vaccine and possibly protects against new variants of SARS-CoV-2.

Note:
Funding: None.

Declaration of Interests: None.

Ethics Approval Statement: Approval of the study protocol was obtained by the ethics committee of the scientific council of the G. Gennimatas General Hospital (protocol number:1/13.1.2021).

Trial Registration: The trial is registered on the International Standard Randomized Controlled Trial Number registry (study ID: ISRCTN61884303).

Keywords: Pfizer–BioNTech mRNA COVID-19 vaccine, immunogenicity, antibody titers, SARS-CoV-2, 3rd dose, booster dose, healthcare workers, Greece

Suggested Citation

Kontopoulou, Konstantina and Nakas, Christos and Papazisis, Georgios, Significant Increase of Antibody Titers After the 3rd Booster Dose of the Pfizer–BioNTech mRNA COVID-19 Vaccine in Healthcare Workers in Greece (December 19, 2021). Available at SSRN: https://ssrn.com/abstract=3989286 or http://dx.doi.org/10.2139/ssrn.3989286

Konstantina Kontopoulou

G. Gennimatas General Hospital ( email )

Eth. Aminis 41
Thessaloniki, 54635
Greece

Christos Nakas

University of Bern - University Institute of Clinical Chemistry ( email )

Bern
Switzerland

University of Thessaly ( email )

Gaiopolis Campus
Larissa, 41110
Greece

Georgios Papazisis (Contact Author)

Aristotle University of Thessaloniki - Department of Clinical Pharmacology ( email )

Greece

Clinical Trials Unit, Special Unit for Biomedical Research and Education, School of Medicine, Aristotle University

University Campus
S. Kyriakidi 1
Thessaloniki, Thessaloniki
Greece

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