Delta caused 82% Covid cases in 3 months: Data

According to data from INSACOG,over all, nearly two in three coronavirus disease (Covid-19) infections in the country so far have been caused by mutated variants.

Nearly 8 of every 10 (82%) of Covid-19 infections in the past three months (May, June and July) were caused by the highly infectious Delta variant of the SARS-Cov-2 virus according to data from the Indian Sars-CoV-2 Genomic Consortium or INSACOG dashboard -- highlighting that most cases in India are now being caused by this variant of concern which is also behind the recent surge of cases in the US.

A BMC health worker collects swab samples for Covid-19 test of passengers arriving from outstation trains at CSMT station, in Mumbai on July 14, 2021. (HT PHOTO)

In March, the Alpha variant was the dominant strain of the virus; in the past three months, only 0,54% of the cases were of this variant.

To be sure, this data pertains to infections where the viral genome was sequenced. This sampling can be considered to be representative, though.

Over all, nearly two in three coronavirus disease (Covid-19) infections in the country so far have been caused by mutated variants, according to data from INSACOG. The consortium of 28 laboratories across the country sequenced 46,124 samples till July 22 (from the time the body started sequencing viral genomes), according to data provided by the minister for state of science and technology Dr Jitendra Singh on Friday.

Of these, 26,957 or 58.4% were found to be either variants of concern or variants of interest.

Of the total samples sequenced, 37.2% were of delta variant. In recent months, that proportion increased sharply.

“This is not unexpected because it is the fastest spreading virus and has replaced almost all other variants across the world. Almost 80% of the cases in Indonesia, US, UK at the moment are caused by the Delta variant. South Africa also has Delta now; the second wave there was driven by Beta and the third by Delta ,” said Dr T Jacob John, former head of the department of virology at Christian Medical College-Vellore.

The fact that the variant was behind India’s bruising second wave of infections may help the country now.

“The Delta plus variant, which is essentially same as Delta, is unlikely to drive a surge in India,” added Dr John.

Interestingly, the proportion of Delta, reduced in July with only 73% of the samples being of the variant. But this was not because the variant was being replaced.

“There were very few samples (in July, including) some that were not of good quality so it becomes difficult to assign lineage,” said Dr Anurag Agarwal, director, Institute of Genomics and Integrative Biology, one of the 28 labs of INSACOG.

There were 4,172 samples of the Alpha variant that was dominant in Northern India, especially Punjab, at the beginning of the year and was then replaced by the Delta variant. INSACOG has so far detected 217 cases of Beta variant that was first reported in South Africa and 1 of Gamma variant first detected in Brazil. Of the total samples, 5,398 were that of variants of interest such as the Kappa variant, close relative of the delta variant.

The consortium has so far sequenced 70 samples of Delta plus variant, which is also considered to be variant of concern.

The highest number of Delta plus cases has been reported from Maharashtra, which accounts for 23 of the 70 cases. This was followed by Madhya Pradesh with 11, and Tamil Nadu with 10.