What should I know about the Delta variant?

It’s a version of the coronavirus that has been found in more than 80 countries since it was first detected in India. It got its name from the World Health Organisation (WHO), which names notable variants after letters of the Greek alphabet.

Viruses constantly mutate and most changes aren’t concerning. But there is a worry that some variants might evolve enough to be more contagious, cause more severe illness or evade the protection that vaccines provide.

Read: India says new Covid Delta Plus variant is a concern

Experts say the Delta variant spreads more easily because of mutations that make it better at latching onto cells in our bodies. In the United Kingdom, the variant is now responsible for 90 per cent of all new infections.

In the US, it represents 20pc of infections, and health officials say it could become the country’s dominant type as well.

"It’s not clear yet whether the variant makes people sicker since more data needs to be collected," said Dr Jacob John, who studies viruses at the Christian Medical College at Vellore in southern India.

Will vaccines help?

Studies have shown that the available vaccines work against variants, including the Delta variant.

Researchers in England studied how effective the two-dose AstraZeneca and Pfizer-BioNTech vaccines were against it, compared with the alpha variant that was first detected in the UK.

The vaccines were protective for those who got both doses, but were less so among those who got one dose.

It’s why experts say it’s important to be fully vaccinated. And it’s why they say making vaccines accessible globally is so critical.

What is Delta Plus?

The variant, called "Delta Plus" in India, was first reported in a Public Health England bulletin on June 11.

It is a sub-lineage of the Delta variant first detected in India and has acquired the spike protein mutation called K417N which is also found in the Beta variant first identified in South Africa.

Some scientists worry that the mutation, coupled with other existing features of the Delta variant, could make it more transmissible.

"The mutation K417N has been of interest as it is present in the Beta variant (B.1.351 lineage), which was reported to have immune evasion property," India's health ministry said in a statement.

Shahid Jameel, a top Indian virologist, said the K417N was known to reduce the effectiveness of a cocktail of therapeutic monoclonal antibodies.

Where all has it been found?

As of June 16, at least 197 cases has been found from 11 countries: Britain (36), Canada (1), India (8), Japan (15), Nepal (3), Poland (9), Portugal (22), Russia (1), Switzerland (18), Turkey (1), the United States (83).

India said on Wednesday around 40 cases of the variant have been observed in the states of Maharashtra, Kerala and Madhya Pradesh, with "no significant increase in prevalence". The earliest case in India is from a sample taken on April 5.

Britain said its first 5 cases were sequenced on April 26 and they were contacts of individuals who had travelled from, or transited through, Nepal and Turkey.

No deaths were reported among the UK and Indian cases.

What are the worries?

Studies are ongoing in India and globally to test the effectiveness of vaccines against this mutation.

"WHO is tracking this variant as part of the Delta variant, as we are doing for other Variants of Concern with additional mutations," the body said in a statement sent to Reuters.

"For the moment, this variant does not seem to be common, currently accounting for only a small fraction of the Delta sequences [...] Delta and other circulating Variants of Concern remain a higher public health risk as they have demonstrated increases in transmission," it said.

But India's health ministry warned that regions where it has been found "may need to enhance their public health response by focusing on surveillance, enhanced testing, quick contact-tracing and priority vaccination."

There are worries Delta Plus would inflict another wave of infections on India after it emerged from the world's worst surge in cases only recently.

"The mutation itself may not lead to a third wave in India - that also depends on COVID-appropriate behaviour, but it could be one of the reasons," said Tarun Bhatnagar, a scientist with the state-run Indian Council for Medical Research.