The impact of comorbidity status in COVID-19 vaccines effectiveness before and after SARS-CoV-2 omicron variant in northeastern Mexico: a retrospective multi-hospital study oleh Maria Elena Camacho-Moll, Viviana Leticia Mata-Tijerina, Carlos Cuauhtémoc Gutiérrez-Salazar, Beatriz Silva-Ramírez, Katia Peñuelas-Urquides, Laura González-Escalante, Brenda Leticia Escobedo-Guajardo, Jorge Eleazar Cruz-Luna, Roberto Corrales-Pérez, Salvador Gómez-García, Mario Bermúdez-de León