Homologous versus heterologous prime-boost COVID-19 vaccination: impact on clinical severity of Omicron among hospitalized COVID-19 patients in Belgium, Meurisse, Marjan, Van Goethem Nina, Van Loenhout Joris, Braeye Toon, and Catteau Lucy , European Society of Clinical Microbiology and Infectious Diseases, 17/04/2023, (2023)