A national population-based study of mortality and risk factors in COVID-19-hospitalized patients in Spain (2020–2021) - Ramos-Rincón, José-Manuel; Sánchez-Paya, José; González-De-La-Aleja, Pilar; Rodríguez-Díaz, Juan-Carlos; Merino, Esperanza (Frontiers in Public Health, 2025)