AY.4 Delta sub-lineage now predominant in UK and Australia, rising in the US A post on the AY.4 sub-lineage of the Delta Sars-Cov-2 variant. More... August 29, 2021August 30, 2021 Coronaheadsup.com Africa, America, Asia, Australasia, Australia, AY.4, B.1.617.2, B.1.617.2.4, Coronavirus, Delta-AY.4, Europe, Infection, Transmission, UK, USA