Study of Immune Response in Subjects Vaccinated Against SARS-CoV-2 Infection

NCT07049497 | Completed

• 1 other identifier: BioVAC-immunity
• Study Type: observational
• Target: 127
• Locations: 1 country
• Sites: 1

Brief Summary

Twelve months after the first SARS-CoV-2 cases in Wuhan, the FDA approved the first COVID-19 vaccine (Pfizer-BioNTech). Early studies on healthcare workers showed that antibody levels, especially against the Spike protein, declined within six months, particularly in those without prior infection. However, previously infected individuals had stronger and longer-lasting responses. The vaccine induces a Th1-type T cell response, linked to milder disease, and activates follicular helper T cells and B cell responses, although antibody levels drop over time. Immune responses also differ by sex, with females showing stronger humoral responses. Key priorities include understanding humoral fluctuations, characterizing cellular immunity, and correlating both responses.

Conditions

SAR-CoV-2; Cellular Immune Response; Antibody Response

Outcome Measures

Primary Outcomes (1)

• To assess the existence of a correlation between the antibody titer six months after the second dose and the T and B cell responses

  Correlation between antibody titer, in terms of antibodies directed against the Spike protein, and T cell response, in terms of IFN-γ measured by ELISpot, as well as B cell response, in terms of frequency and phenotype, assessed six months after the second dose (T3)

  Six months after the second vaccine dose, which coincides with the time of enrollment

Study Arms (2)

107 healthcare workers who completed the vaccination cycle for SARS-CoV-2

T cell response in terms of IFN-γ measured by ELISpot

Other: Evaluation of the T cell response in terms of IFN-γ measured by ELISpot

20 healthy donors who didn't receive SARS-CoV-2 vaccination

T cell response in terms of IFN-γ measured by ELISpot

Other: Evaluation of the T cell response in terms of IFN-γ measured by ELISpot

Interventions

Evaluation of the T cell response in terms of IFN-γ measured by ELISpot OTHER

The evaluation of the T cell response will be performed by quantifying the frequencies of SARS-CoV-2-specific T cells producing IFN-γ using an enzyme-linked immunospot assay (ELISpot), with cryopreserved PBMC collected at the designated timepoints (T0, T1, T2, T3, and T4)

107 healthcare workers who completed the vaccination cycle for SARS-CoV-2; 20 healthy donors who didn't receive SARS-CoV-2 vaccination

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Approximately 405 biological samples will be analyzed in the study, collected from the OSR Biobank (with protocol related to the BioVAC study approved by the Ethics Committee: 17/INT/2022). These samples were obtained from healthcare workers who completed the SARS-CoV-2 vaccination cycle between January 2020 and November 2021.

You may qualify if:

• Male and/or female sex
• Age ≥18 years
• Completion of the SARS-CoV-2 vaccination cycle with the Pfizer-BioNTech vaccine
• Informed consent for the storage of biological material at the San Raffaele Hospital Biological Resource Center (with protocol related to the BioVAC study approved by the Ethics Committee: 17/INT/2022)
• Availability of at least two aliquots of PBMC collected at the completion of the vaccination cycle and frozen at the CRB

You may not qualify if:

• none donor group
• \- consent for sample collection and storage in the Biobank between 2016 and 2018
• none

Sponsors & Collaborators

• IRCCS San Raffaele: lead

Study Sites (1)

IRCCS Ospedale San Raffaele

Milan, Italy, 20132, Italy

Location

Biospecimen

Retention: SAMPLES WITHOUT DNA

Aliquots of PBMC collected at the completion of the vaccination cycle and frozen at the CRB

Study Officials

• Patrizia Rovere Querini, PhD, MD

  IRCCS Ospedale San Raffaele

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: MD, PhD

Study Record Dates

• First Submitted: June 25, 2025
• First Posted: July 3, 2025
• Study Start: June 28, 2022
• Primary Completion: July 20, 2022
• Study Completion: May 15, 2024
• Last Updated: July 14, 2025

Record last verified: 2025-06

Data Sharing

• IPD Sharing: Will not share

Locations

IT (1)