Total Anti-SARS-CoV-2 Antibodies Measured 6 Months After Pfizer-BioNTech COVID-19 Vaccination in Healthcare Workers

7 Pages Posted: 3 Sep 2021

See all articles by Gian Luca Salvagno

Gian Luca Salvagno

University of Verona

Brandon M. Henry

Cincinnati Children's Hospital Medical Center

Laura Pighi

University of Verona - Verona University Hospital

Simone De Nitto

University of Verona

Giuseppe Lippi

University of Verona

Date Written: September 1, 2021

Abstract

Background: This study was aimed at monitoring the kinetics of serum total anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antibodies in a cohort of healthcare workers after voluntary vaccination with Pfizer-BioNTech coronavirus disease 2019 (COVID-19).

Methods: The study population consisted of 787 healthcare workers (mean age 44±12 years; 66% females), who received two 30 μg doses of Pfizer-BioNTech COVID-19 vaccine, 3 weeks apart. Venous blood was drawn before the first vaccine dose, immediately before the second vaccine dose, and then at 1, 3 and 6 months after the second vaccine dose. Serological testing was based on total anti-SARS-CoV-2 antibodies measurement with Roche Elecsys Anti-SARS-CoV-2 S chemiluminescent immunoassay, on Roche Cobas 6000 (positive result: ≥0.8 KU/L).

Results: The median serum levels of total anti-SARS-CoV-2 antibodies reached the peak (1762 KU/L) 1 month after the second vaccine dose, but tended to progressively decline at the 3-month (1086 KU/L) and 6-month (802 KU/L) follow-up points. Overall, the values after 3- and 6-months were 37% and 57% lower than the corresponding concentrations measured at the peak. No healthcare worker had total anti-SARS-CoV-2 antibodies below the method-dependent cut-off. The decline compared to the peak was more accentuated in baseline seropositive persons than in those who were baseline seronegative (74% vs. 52%) cohort. The 6-month post-vaccination anti-SARS-CoV-2 antibodies in subjects aged <65 years remained over 2-fold higher than that measured in those aged ≥65 years (813 vs. 343 KU/L).

Conclusion: A gradual decline of total anti-SARS-CoV-2 antibodies occurred 6 months after vaccination, though antibodies values remained considerably higher than the method-dependent cut-off and no seronegativization could be recorded.

Note: Funding: None.

Declaration of Interests: The authors declare no conflict of interest.

Ethics Approval Statement: All study participants gave informed consents for vaccination and undergoing serial anti-SARS-CoV-2 antibodies monitoring. The study was conducted in accordance with the Declaration of Helsinki and cleared by the Ethics Committee of Verona and Rovigo Provinces (3246CESC).

Keywords: COVID-19, SARS-CoV-2, Vaccination, Antibodies, Immune response

Suggested Citation

Salvagno, Gian Luca and Henry, Brandon and Pighi, Laura and De Nitto, Simone and Lippi, Giuseppe, Total Anti-SARS-CoV-2 Antibodies Measured 6 Months After Pfizer-BioNTech COVID-19 Vaccination in Healthcare Workers (September 1, 2021). Available at SSRN: https://ssrn.com/abstract=3915349 or http://dx.doi.org/10.2139/ssrn.3915349

Gian Luca Salvagno

University of Verona ( email )

Via dell'Artigliere, 8
Verona, 37129
Italy

Brandon Henry

Cincinnati Children's Hospital Medical Center ( email )

3333 Burnet Avenue
Cincinnati, OH 45229
United States

Laura Pighi

University of Verona - Verona University Hospital ( email )

Italy

Simone De Nitto

University of Verona ( email )

Via dell'Artigliere, 8
Verona, 37129
Italy

Giuseppe Lippi (Contact Author)

University of Verona ( email )

Section of Clinical Biochemistry
Ospedale Policlinico GB Rossi
Verona, VR 37124
Italy

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