show Abstracthide AbstractSARS-CoV-2 infection activates interferon-controlled signaling pathways and elicits a wide spectrum of immune responses and clinical manifestations in human patients. Here, we investigate the impact of prior vaccination on the innate immune response of hospitalized COVID-19 patients infected with the SARS-CoV-2 Beta variant through RNA sequencing of Peripheral Blood Mononuclear Cells. Four patients had received the first dose of BNT162b about 11 days prior to the onset of COVID-19 symptoms and five patients were unvaccinated. Patients had received dexamethasone treatment. Immune transcriptomes were obtained at days 7-13, 20-32 and 42-60 after first symptomology. RNA-seq revealed an enhanced JAK-STAT-mediated immune transcriptome response at day 10 in vaccinated patients as compared to unvaccinated ones. This increase had subsided by day 35. Expression of the genes encoding the antiviral protein oligoadenylate synthetase (OAS) 1, which is inversely correlated with disease severity, and other key antiviral proteins was increased in the vaccinated group. We also investigated the immune transcriptome in naïve individuals receiving their first dose of BNT162b and identified a gene signature shared with the vaccinated COVID-19 patients. Our study demonstrates that RNA-seq can be used to monitor molecular immune responses elicited by the BNT162b vaccine, both in naïve individuals and in COVID-19 patients, and it provides a biomarker-based approach to systems vaccinology. Overall design: RNA-seq were performed with peripheral blood mononuclear cells (PBMCs) of COVID-19 patients infected by SARS-CoV-2 Beta varient (Beta) and SARS-CoV-2 naïve vaccinated individuals.