BA.4/BA.5 early surge report Austria

More than two years into the COVID-19 pandemic, the emergence of the Omicron subvariants BA.4 and BA.5 initiated the fifth wave. BA.4/BA.5 share identical spike proteins and are thus difficult to differentiate using standard diagnostic tests. The true frequency and diversity of the two variants in Austria is therefore largely unknown. Aim of this report is to take stock about the frequency and diversity of BA.4 & BA.5 and their subvariants based on whole genome sequencing (WGS) data as deposited at GISAID database. Results show that most sequenced cases belong to BA.5 (c. 86 %) rather than BA.4 (c. 14 %) and that most of the global diversity (24 out of 32 subvariants) of BA.4 and BA.5 in terms of subvariants described is already present in Austria. However, most cases can be attributed to a few subvariants (e.g. BA.5.1, BE.1.1, BA.5.3, BA.5.2.1) with high estimated growth advantage over BA.2 (ranging 103 to 159 %) and may be worth monitoring as the immediate wave unfolds.