4. CEU Escuela Internacional de Doctorado (CEINDO)

The latest global pandemic of all is the well-known COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and originated in the city of Wuhan in December 2019. The need to find treatments and immunization tools was crucial. Quantifying the levels, duration, and effectiveness of immune responses against SARS-CoV-2 in each country was decisive in establishing, for example, vaccination intervals or understanding the long-term effects on the population, as well as anticipating the risk of future infection outbreaks with the arrival of new variants. The main objective of this thesis was to establish the specific activation level of T cells focused on vaccination against SARS-CoV-2 in Spain by developing a rapid cellular test starting from a minimally processed sample, such as whole blood. Furthermore, this test was not only performed on healthy volunteers but also on a vulnerable cohort (long-term hemodialysis patients) and, in a heterologous vaccination scenario. Moreover, the levels of specific antibodies against the S protein of the virus in each individual were checked for comparison.