MUMBAI: The AY.1 and AY.2 sub-lineages of the Delta variant are unlikely to be more transmissible than their highly communicable parent, the Indian SARS-CoV2 Genomics Consortium (Insacog) said in its latest bulletin.
The detection of 21 cases of the AY.1 sub-lineage, called ‘Delta plus’, in June had stoked fears of increased transmission or even an early onset of the third wave in Maharashtra. A month later, districts where Delta plus cases were found have not seen any unusual surge in cases or deaths in those pockets.
In fact, of all the samples sequenced from the state in June, up to 88% were found positive for the Delta variant and not many for Delta plus. What has also bolstered the belief that Delta plus is not as transmissible as Delta is the fact that some of the cases were detected as early as April; only their genome sequencing reports came in June.
The Insacog update said the Delta sub-lineages AY.1 and AY.2 were declining globally with near zero cases in the last week of June in both the UK and US. “There are no indications of rising trend in the four clusters (in Ratnagiri and Jalgaon in Maharashtra, Bhopal in MP and Chennai in TN),” the update added.
The Delta Plus and AY.2 sub-lineages continue to account for less than 1% of genomic sequences carried out from June, said Insacog. Delta (B 1617.2), which was first isolated in Vidarbha and has driven the second wave, continues to be the dominant lineage in the country and one that is also rapidly rising globally.
Districts corroborated that they have not been flooded with cases or cluster infections as they had feared. Of the 21 cases of Delta Plus in the state, Ratnagiri reported the highest (9), followed by Jalgaon (7), Mumbai (2), and one each in Palghar, Sindhudurg and Thane. An 80-year-old woman from Ratnagiri, who was infected with the Delta Plus strain, succumbed.
Of the 1,400-odd June Covid samples processed in the state, as many as 88% (1,195) were positive for the Delta variant. A state official said they are awaiting reports for another 2,200 samples. The Delta variant, believed to have originated in Vidarbha, was found in 87% of samples sequenced in May as well.
Maharashtra has tied up with the CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), New Delhi, to carry out sequencing of 3,600 samples in a month. The Covid-19 Genome Surveillance portal maintained by the CSIR-IGIB shows that around 7,900 samples have been sequenced from Maharashtra in 2021.
In Ratnagiri, where all Delta Plus cases were found from six villages in one taluka, Sangameshwar, officials said they have not been alerted of any new cases. While the district continues to report 300-400 cases every day at present, they are from other areas such as Chiplun, Ratnagiri city and some villages.
Jalgaon officials said Vichkheda village that reported all the seven Delta Plus cases is not seeing even cases of fever or influenza-like illnesses now. After the Delta Plus cases were found, the authorities had carried out a fresh round of tests in the villages, where two positive cases were found. Dr D S Potode, assistant district health officer, said those samples were sent for genome sequencing, but they haven’t got an update. The entire district of Jalgaon is reporting less than a dozen Covid cases daily.