Breakthrough infections of coronavirus cases comprise a very high proportion of the Delta variant, the INSACOG, a genome sequencing government consortium of laboratories, has said.

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The continuing COVID-19 outbreaks across India are attributable to the Delta variant, a susceptible population and reduced vaccine effectiveness in blocking transmission, the INSACOG added. However, vaccination continues to be very effective in reducing severe disease and death, and public health measures to reduce transmission and inoculation remain critical, the INSACOG stressed in its latest bulletin dated August 16.

"As of now, sequencing of vaccination breakthroughs in India is also showing a very high proportion of Delta variant. Investigations for any new variants are ongoing," the INSACOG said. Of the 30,230 samples of Variants of Concern and Variants of Interest sequenced by the INSACOG, 20,324 were of Delta, it said. The Delta variant is currently driving the pandemic across several countries with China and Korea seeing new highs. Korea has reported that the new surge is due to Delta plus K417N mutation.

The Delta variant resulted in a deadly second wave in the country between March to May that wreaked havoc on the health infrastructure, overwhelming hospitals. It infected lakhs and killed thousands. In India, new cases of AY.1, AY.2, AY.3 (Delta Plus) are being seen in July samples from Maharashtra at a frequency of about 1 per cent. However, at this time none of these sub-lineages has been found to have a growth advantage over the Delta parent lineage, it noted.

According to INSACOG (the Indian SARS-CoV2 Genomics Consortium), 61 samples of Delta Plus variants have been detected in the country so far. "Delta variant is the major VOC in India at this time. Continuing outbreaks across India are attributable to Delta, a susceptible population, reduced vaccine effectiveness in blocking transmission, and opportunities for transmission," the INSACOG said.

Daily coronavirus cases have seen a significant plunge since the second wave which peaked in May. The active cases have declined to 3,63,605, the lowest in 150 days, and comprise 1.12 per cent of the total infections, the lowest since March 2020, the Health Ministry said on 20 August. Over 57 crore jabs have been administered in the country so far, the Health Ministry added. The R-Value, or the Reproduction rate in the country has also dipped to 0.89 from August 14-16. But the country continues to post over 25,000 cases every day. There has been a concern whether increasing vaccination breakthroughs in India are because of a new variant, the INSACOG said.

It also cited an example of the UK. With a population of about 6.7 crores, the UK has reported about 18 lakh cases and 1.2 lakh vaccination breakthroughs with Delta since April 2021. "Thus, vaccination breakthroughs are common during Delta outbreaks and are expected in India as well," it said.