The latest derivative of the Delta variant (B1617.2) appeared in India, having previously spread in Israel. Named AY.12, this variant is found in a number of states in India. Some cases of Delta variant in India, currently reclassified to AY.12.
Today, the Delta variant family has grown to at least 12 sub-lineages. This includes AY.1 which was formerly known as ‘Delta Plus’. In India, the first case of AY.12 was identified in September 2020. As of 26 August 2021, a total of 44,083 sequences with similar lineage were found worldwide. Currently, AY.12 is referred to as the most dominant strain in Israel. Approximately 51 percent of the sample studied had this variance.
Basically, AY is an alias for the Delta variant. One of the derivatives of the Delta variant which is also known as the AY code is the Delta Plus variant which has the official name AY.1. According to INSACOG, it is not clear whether AY.12 is clinically different from the delta variant or B1617.2. However, this AY.12 has lost some of the mutations seen in the Delta lineage, such as G142D in its spike protein. INSACOG also said no new mutations were observed in the spike protein of this strain. However, its growth is very fast in Israel, so it should be examined further.