Co-infection of chlamydia pneumoniae and mycoplasma pneumoniae with SARS-CoV-2 is associated with more severe features. - De Francesco MA; Poiesi C; Gargiulo F; Bonfanti C; Pollara P; Fiorentini S; Caccuri F; Carta V; Mangeri L; Pellizzeri S; Rizzoni D; Malerba P; et al. (The Journal of infection, 2021)