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

Completed

• Conditions: Cellular Immune Response; Antibody Response; SAR-CoV-2

• Registration Number: NCT07049497
• Lead Sponsor: IRCCS San Raffaele

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.

Detailed Description

Not available

Study Timeline

• Study Start: 2022-06-28
• Primary Completion: 2022-07-20
• Study Completion: 2024-05-15
• Status Verified: 2025-06
• Study First Submitted: 2025-06-25
• Study First Submitted QC: 2025-06-25
• Last Update Submitted: 2025-06-25
• Study First Posted: 2025-07-03
• Last Update Posted: 2025-07-03

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 127

Inclusion Criteria

• 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

Exclusion Criteria

• none donor group

Inclusion Criteria:

• consent for sample collection and storage in the Biobank between 2016 and 2018

Exclusion Criteria:

• none

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
To assess the existence of a correlation between the antibody titer six months after the second dose and the T and B cell responses	Six months after the second vaccine dose, which coincides with the time of enrollment	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)

Trial Locations

Locations (1)

IRCCS Ospedale San Raffaele; 🇮🇹 Milano, Italy