The Omicron BA.4 and BA.5 subvariants of SARS-CoV-2 are better at evading human immune defenses than any of their predecessors. However, recent research shows that a previous infection with another variant still provides some protection against re-infection with BA.4 or BA.5 & a previous infection with omicron protects against re-infection.
The researchers examined all COVID 19 cases in Qatar that have occurred since the start of the BA.4 and BA.5 infection wave & discovered that infection with a pre-Omicron variant prevented reinfection with BA.4 or BA.5 with an efficacy of 28.3 % and symptomatic reinfection with either subvariant with an efficacy of 15.1 %. Prior infection with Omicron conferred greater protection, protecting 79.7 % of subjects from reinfection with BA.4 and BA.5 and 76.1 % of participants from symptomatic progression
