Longitudinal immunogenicity cohort study of SARS-CoV-2 mRNA vaccines across individuals with different immunocompromising conditions: heterogeneity in the immune response and crucial role of Omicron-adapted booster doses.

Abstract

Background: Individuals with primary and secondary immunodeficiencies, being more susceptible to infections, are a priority for vaccination. Here, we determined and compared in a longitudinal study the immune response elicited by SARS-CoV-2 vaccination across different groups of individuals who are immunocompromised.

Methods: In the PatoVac_COV longitudinal prospective single-centre study, the spike-specific B cell and antibody responses to SARS-CoV-2 mRNA vaccination were compared across 5 different groups of individuals with haematological malignancies, hematopoietic stem cell (HCT) or solid organ transplantation (SOT), undergoing haemodialysis, and people living with HIV (PLWH), for a total of 585 participants. Data from participants who were immunocompromised were compared to a group of 123 participants who were immunocompetent. Blood samples were collected before and after each vaccine administration, up to 2 years.

Findings: A different immune responsiveness was observed after the first two vaccine doses, with haematological, haemodialysis, and SOT participants showing reduced responsiveness compared to HCT and PLWH, and relative to the comparison group. Spike-specific B cell response was both slower and lower in all groups except in PLWH when compared to participants who were immunocompetent. However, the first booster dose enhanced both the B and the antibody responses in all groups, that persisted up to 2 years after the first vaccine administration. The administration of Omicron-adapted booster vaccines promoted a primary BA.2 RBD-specific B cell response, especially in participants who were immunocompromised. Despite repeated vaccinations, a subset of persistent low-responders, especially among SOT, was identified.

Interpretation: Our study highlights the heterogeneous immune response across individuals with different pathologies, the pivotal role of the first booster dose, the primary activation of Omicron-specific B cells elicited by updated variant-adapted vaccines and the persistence of low-responders despite multiple vaccine administrations. These aspects have a clinical relevance for planning vaccination schedules tailored for individuals with different immunocompromising conditions.

Funding: This work was supported by funds from the Department of Medical Biotechnologies of the University of Siena, and from EU within the NextGenerationEU-MUR PNRR Tuscany Health Ecosystem (Project no ECS00000017-THE).