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Mucosal Immune Response in BNT162b2 COVID-19 Vaccine Recipients

16 Pages Posted: 29 Jun 2021

See all articles by Lorenzo Azzi

Lorenzo Azzi

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Daniela Dalla Gasperina

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Giovanni Veronesi

University of Insubria - Research Centre in Epidemiology and Preventive Medicine (EPIMED)

Mariam Shallak

University of Insubria - Laboratory of General Pathology and Immunology “Giovanna Tosi”

Giuseppe Ietto

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Domenico Iovino

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Andreina Baj

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Francesco Gianfagna

University of Insubria - Research Centre in Epidemiology and Preventive Medicine (EPIMED)

Daniele Focosi

Pisa University Hospital

Fabrizio Maggi

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Marco Mario Ferrario

University of Insubria - Research Centre in Epidemiology and Preventive Medicine (EPIMED)

Francesco Dentali

University of Insubria - Department of Medicine and Surgery

Giulio Carcano

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Angelo Tagliabue

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi

Lorenzo Stefano Maffioli

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi, Chief Medical Officer

Roberto Sergio Accolla

University of Insubria - Laboratory of General Pathology and Immunology “Giovanna Tosi”

Greta Forlani

University of Insubria - Laboratory of General Pathology and Immunology “Giovanna Tosi”

More...

Abstract

Background: Although the BNT162b2 COVID-19 vaccine is known to induce IgG neutralizing antibodies in serum protecting against COVID-19, it has not been studied in detail whether it could generate specific immunity at mucosal sites, which represent the primary route of entry of SARS-CoV-2. 

Methods: Samples of serum and saliva of 60 BNT162b2-vaccinated healthcare workers were collected at baseline, two weeks after the first dose and two weeks after the second dose. Anti-S-protein IgG and IgA total antibodies titres and the presence of neutralizing antibodies against the Receptor Binding Domain in both serum and saliva were measured by quantitative and by competitive ELISA, respectively. 

Findings: Complete vaccination cycle generates a similar serum IgG antibody titre as a single dose in previously infected seropositive individuals. Serum IgA concentration reaches a plateau after a single dose in seropositive individuals and two vaccine doses in seronegative subjects. After the second dose IgA level was higher in seronegative than in seropositive subjects. In saliva, IgG level is almost two orders of magnitude lower than in serum, reaching the highest values after the second dose. IgA concentration remains low and increases significantly only in seropositive individuals after the second dose. Neutralizing antibody titres were much higher in serum than in saliva. 

Interpretation: The mRNA BNT162b2 vaccination elicits a strong systemic immune response by drastically boosting neutralizing antibodies development in serum, but not in saliva, indicating that at least oral mucosal immunity is poorly activated by this vaccination protocol, thus failing in limiting virus acquisition upon its entry through this route.

Funding Information: This study was funded by our public Institution, Department of Medicine and Surgery, University of Insubria.

Declaration of Interests: None to declare.

Ethics Approval Statement: The clinical protocol for sample and data collection and the informed consent were approved by the Institutional Ethics Committee (Comitato Etico dell’Insubria, n° 165/2020).

Keywords: BNT162b2 mRNA vaccine; COVID-19; SARS-CoV-2; saliva; IgA

Suggested Citation

Azzi, Lorenzo and Dalla Gasperina, Daniela and Veronesi, Giovanni and Shallak, Mariam and Ietto, Giuseppe and Iovino, Domenico and Baj, Andreina and Gianfagna, Francesco and Focosi, Daniele and Maggi, Fabrizio and Ferrario, Marco Mario and Dentali, Francesco and Carcano, Giulio and Tagliabue, Angelo and Maffioli, Lorenzo Stefano and Accolla, Roberto Sergio and Forlani, Greta, Mucosal Immune Response in BNT162b2 COVID-19 Vaccine Recipients. Available at SSRN: https://ssrn.com/abstract=3871718 or http://dx.doi.org/10.2139/ssrn.3871718

Lorenzo Azzi (Contact Author)

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Daniela Dalla Gasperina

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Giovanni Veronesi

University of Insubria - Research Centre in Epidemiology and Preventive Medicine (EPIMED) ( email )

Varese
Italy

Mariam Shallak

University of Insubria - Laboratory of General Pathology and Immunology “Giovanna Tosi” ( email )

Varese
Italy

Giuseppe Ietto

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Domenico Iovino

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Andreina Baj

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Francesco Gianfagna

University of Insubria - Research Centre in Epidemiology and Preventive Medicine (EPIMED) ( email )

Varese
Italy

Daniele Focosi

Pisa University Hospital ( email )

via Paradisa 2
Pisa, 56124
Italy

Fabrizio Maggi

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Marco Mario Ferrario

University of Insubria - Research Centre in Epidemiology and Preventive Medicine (EPIMED) ( email )

Varese
Italy

Francesco Dentali

University of Insubria - Department of Medicine and Surgery ( email )

Varese
Italy

Giulio Carcano

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Angelo Tagliabue

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi ( email )

Varese
Italy

Lorenzo Stefano Maffioli

University of Insubria - Azienda Socio-Sanitaria Territoriale dei Sette Laghi, Chief Medical Officer ( email )

Varese
Italy

Roberto Sergio Accolla

University of Insubria - Laboratory of General Pathology and Immunology “Giovanna Tosi” ( email )

Varese
Italy

Greta Forlani

University of Insubria - Laboratory of General Pathology and Immunology “Giovanna Tosi” ( email )

Varese
Italy

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