Delta sub-lineages AY.1, AY.2 unlikely to be more transmissible, says INSACOG as cases decline
In a recent bulletin, the Indian Sars-CoV-2 Genomics Consortium (INSACOG) said that the cases of Delta sub-lineages AY.1 and AY.2 are declining globally.
The AY.1 and AY.2 sub-lineages of the highly contagious Delta variant of Sars-Cov-2 are unlikely to be more transmissible than Delta itself, said the consortium of government panels involved in genome sequencing of coronavirus. In a recent bulletin, the Indian Sars-CoV-2 Genomics Consortium (INSACOG) said that the cases of Delta sub-lineages AY.1 and AY.2 are declining globally, with near-zero cases in the last week of June in the UK and the US where they were most frequently detected.
“They also continue to be below 1% in available sequences from June in India. It is likely that neither AY.1 nor AY.2 is more transmissible than Delta,” the INSACOG said.
The emergence of AY.1, also known as the Delta Plus variant, caused concern for health authorities due to the lack of data on its transmissibility factor and risks associated with it. While experts had said there was no immediate cause of concern due to low incidence in the country, they had stressed the need for more studies on the Delta Plus variant before reaching any conclusion on its transmissibility and ability to evade pre-existing immunity.
The Delta Plus variant characterised by B.1.617.2 variant acquiring another mutation, K417N, also found in the B.1.351 or Beta variant. The earliest sequence of this genome was found in Europe in late March this year. The consortium said that there is no indication of a rising trend in the four identified clusters of Ratnagiri and Jalgaon in Maharashtra, Bhopal in Madhya Pradesh and Chennai in Tamil Nadu.
It also said that AY.3 has been identified as a new Delta sub-lineage, defined by “ORF1a: I3731V common AY.1 mutations except for S: K417.” The AY.3 Delta sub-lineage is primarily seen in the US with single reclassified cases in the UK and India. There are no known significant properties of this mutation, but since it is a Delta VOC sub-lineage, INSACOG will continue to monitor it, the bulletin stated.