The Delta plus variant, a new mutant version of the Delta strain first detected in India, has been found in 22 cases in Maharashtra, Kerala, and Madhya Pradesh and is a "variant of concern", the government said in a warning to these states on Tuesday evening.
At a time India is emerging from the deadly second wave of Covid and cases have dropped, Delta Plus cases have been found in Maharashtra's Ratnagiri and Jalgaon; in Palakkad and Pathanamthitta in Kerala; and in Bhopal and Shivpuri in Madhya Pradesh, the government said in its advisory.
"The Chief Secretaries of the states have been advised to take up immediate containment measures in these districts and clusters, as identified by INSACOG (Indian SARS-CoV-2 Genomic Consortia), including preventing crowds and intermingling of people, widespread testing, prompt tracing as well as vaccine coverage on priority basis," the note said.
"The Centre has sent an advisory to these states about their public health response. The measures, while broadly remaining the same as have been implemented by them earlier, have to become more focused and effective. We don't want this small number to take a bigger form," VK Paul, the head of the National Expert Group on Vaccine Administration, told reporters.
Experts in Maharashtra fear the new variant could potentially trigger a third wave and warn it could come earlier than originally predicted.
Maharashtra, which has reported most of these Delta Plus cases, is already preparing for a third wave.
The state is collecting data like travel history and vaccination status of those who have reported this version of the virus.
The worry stems from the fact that very little is known about this strain, which is now in nine countries - US, UK, Portugal, Switzerland, Japan, Poland, Russia and China besides India.
"It is worrisome because we do not know enough about how it is going to behave from here. In the variants that we have seen, there have been some very different scenarios that have presented themselves," said Om Shrivastava, a member of the Maharashtra Task Force on Covid.
"We know that the delta wave in other parts of the world is very infectious and it spreads very rapidly and it can affect a multitude of people within a very short period of time," said Dr Shrivastava.
Maharashtra carried out genome sequencing of 100 samples from each district. "Since May 15, 7,500 samples have been taken in which about 21 cases of delta plus have been found," said Rajesh Tope, Maharashtra Health Minister.
Like the Delta strain, which has now spread to 80 countries, the Delta Plus is considered highly infectious and fast-spreading.
According to INSACOG, the Delta Plus also shows stronger binding to receptors of lung cells and potentially reduced monoclonal antibody response.
It may also show resistance to existing treatment protocol for Covid. There are concerns over whether current vaccines will be effective against the Delta Plus.
The government said while the two vaccines being used in India, Serum Institute of India's Covishield and Bharat Biotech's Covaxin, are effective against the Delta variant, data on how they work on the Delta Plus would be shared later.
"We will share more information with you shortly," said Rajesh Bhushan, Union Health Secretary.
But health experts say the prevalence of this variant is currently low.
While INSACOG classified the Delta Plus as a "Variant of Concern", the Health Secretary did not.
"Right now it's a variant of interest, not a variant of concern," Dr Bhushan said in the Health Ministry briefing.
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