Home >News >India >Delta variant continues to be dominant lineage in new Covid cases across India: INSACOG

The Delta variant of coronavirus continues to be the dominant lineage for fresh cases of Covid-19 across India, while the other Variants of Concern (VoC) are at a lower rate and declining, INSACOG said on Thursday.

The delta variant has spread to at least 90 countries and is 50% more transmissible than the alpha variant, the variant first identified in Kent, which is around 50% more transmissible than the original Covid-19 that caused the pandemic.

INSACOG, a consortium of government panels involved in the genome-sequencing of the coronavirus, has also said that there is no evidence of any new Delta sub-lineage that is of greater concern than Delta at present.

The INSACOG stated: "Delta continues to be the dominant lineage for new cases across all parts of India in recent samples and remains the most rapidly rising lineage globally that is responsible for multiple outbreaks, including across Southeast Asia, which shows the fastest growth in new cases globally."

It also noted that regions with high Covid-19 vaccination and strong public health measures, such as Singapore, continue to do well.

The Delta variant of Covid-19 was behind the deadly second wave in the country that killed thousands and infected lakhs from March to May.

The INSACOG said a study by the Indian Council of Medical Research (ICMR) has confirmed that most of the clinical cases in vaccine breakthrough were infected with the Delta variant but only 9.8% infections required hospitalisation, while fatality was found to be restricted to 0.4%, according to a PTI report.

It added that the data for higher infectivity of Delta continues to grow with the secondary attack rate in household contacts being almost double for Delta, when compared to Alpha (Public Health England, July 9 update). The other VoC continue to be very low in India and are declining relative to Delta globally.

"Public health measures to reduce transmission and vaccination remain critical," the INSACOG stressed.

Lambda variant in India

No cases of the Lambda variant have so far been reported in India. In data from Britain, Lambda is still seen primarily in travellers or their contacts and is not growing relative to Delta.

A growing spectrum of mutations is seen in the Delta background in the UK, the US and India.

The most frequent spike protein mutations, other than K417N (AY.1/AY.2), seen in the UK are G446V and P251L. In India, A222V and K77T have been reported as possible markers of sub-lineages.

Previous research into the A222V mutation for either transmissibility or immune escape was negative. In case of the K77T mutation, it has previously been reported in a cluster of Delta that spread to Asiatic lions in a zoo, and seen in sequences from Tamil Nadu, but has no known impact on transmission or immune escape in humans, the INSACOG said.

How well the vaccines are faring against the delta variant

A new study from the Pasteur Institute in France found that the delta variant is less sensitive to neutralising antibodies (the Y-shaped proteins that latch onto the coronavirus and stop it from entering our cells). The researchers compared three “variants of concern" – alpha, beta and delta – for their sensitivity to different sets of antibodies:

-- antibodies used as drugs to treat people with Covid (monoclonals)

-- antibodies from infected people six months after they recovered

-- antibodies from vaccinated people who were previously infected

-- antibodies from vaccinated people who had not been infected.

With agency inputs

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