Tu21 - Monitoring of Naturally Acquired and Vaccine-induced SARS-CoV-2 Specific Cellular Immune Responses

The current global COVID-19 pandemic has emphasized the importance of widespread cellular immune-monitoring programs for evaluation of immunity upon natural infection and vaccination. Cellular immune-monitoring tools are important for understanding the SARS-CoV-2-induced immune responses and can help provide guidance to clinicians and health authorities about the type, degree, and duration of cellular immunity and thus improve the decision-making about future vaccine programs and the roll-out of booster doses.

We have developed SARS-CoV-2-specific immune-monitoring tools based on the Dextramer^® technology to detect and characterize virus-specific CD4⁺ T cells, CD8⁺ T cells and B cells. The Dextramer^® reagents were clinically evaluated by longitudinal assessment of immunity in individuals previously infected with or vaccinated against SARS-CoV-2. Inspection of the T cell epitopes included in the Dextramer assay showed a high degree of conservation between Wuhan, Delta, and Omicron variants and are minimally affected by mutations.

Our results show that SARS-CoV-2-specific Dextramer^® reagents can detect SARS-CoV-2-specific immune cells in patients previously exposed to SARS-CoV-2 or vaccinated individuals. We found that both COVID-19 infection and vaccination elicit strong immune responses towards SARS-CoV-2, which declines over time. These results are encouraging and will help understanding the longevity of immunity after infection and vaccination. Moreover, the results support the idea of using immune monitoring as a widespread tool for tailoring the vaccine schedule based on the individual’s immunity. The tailored vaccine approach will be further investigated by analysing T-cell specificities using the DNA barcode-based dCODE Dextramer® technology in combination with single cell multi-omics systems.