The present invention relates to new specific 6-6 or 5-6 fused bicyclic compounds comprising pyrimidine or pyridine useful in the prevention and/or treatment of infectious diseases. In particular, the present invention relates to a compound of formula (I) wherein : Ar1 is a (C5-C11)arylene or (C5-C11)heteroarylene group, X is -CH-, -S-, -NR5 or -N-, Y is -CH-, -NR5 -S- or -NR6-CH2-, T is -CH- and Q is -CH- or T is -N- and Q is -CR10- or -N-, provided that one or two of X, Q and Y comprise a heteroatom, and with the proviso that, at least one of R1, R2, and, if present, R5 or R6, contains a group -NH-Alk-NR3R4. The inventors showed that compounds of formula (I) present an activity against both W2 and 3D7 Plasmodium falciparum strains, an activity against T. brucei brucei but also an activity against SARS-CoV-2 virus, and that they are positive for G4 recognition. The invention also relates to the preparation process and to the therapeutic uses of the compounds of formula (I).