What we know about the coronavirus variant contributing to India's surging caseload

India's coronavirus cases continue to rise at an unprecedented rate, putting hospitals in a desperate situation and resulting in Canada clamping down on travel from the country.

The surge is being attributed in part to a new variant that the World Health Organization sayswas first detected in India last fall,though experts remain divided over whether it is the main driver in the country's explosion in cases.

Named B1617,it is currently classified as a "variant of interest" by the WHO and public health officials in Canada, which this week became the latest country to confirm cases of the variant.

Media reports have called it a "double mutant," but many variants have multiple mutations, and with limited data there isn't clear evidence whether this one is more transmissible or deadly.

Here's what you need to know about the new variant.

Why is it considered a variant of interest?

Viruses mutate all the time, and many of the mutations are inconsequential, virologists say.

A variant of interest, however, means that there are mutations in the virus that give it the potential to:

• Be more transmissible compared to the original strain.
• Result in more severe disease compared to the original strain.
• Escape immunity, such as from vaccines or from previous COVID-19 infection.

If more evidence emerges that it does one or more of these things, a variant of interest may be upgraded to a variant of concern.

Variants first detected in the United Kingdom, Brazil and South Africa are considered variants of concern and are being tracked in a running tally on the Public Health Agency of Canada's website.

How widespread is this variant?

Thereis limited data due to the lack of widespread sample testing across India.

Last month, the Health Ministry reported that the variant was found in 15 to 20 per cent of the samples sequenced from hard-hit Maharashtra state, which accounted for more than 60 per cent of all active cases in India.

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Researchers are still not certain if the B1617 coronavirus variant or human behaviour is driving the spike of COVID-19 infections in India, says Dr. Matthew Oughton, an infectious disease specialist at Montreal's Jewish General Hospital.

The variant has also shown up in well over a dozen countries around the world, according to the GISAID global database. They include the United Kingdom, the United States, Singapore and Australia.

In Canada, the B.C. Ministry of Health confirmed on Wednesday there had been 39 B1617 cases reported in the province as of April 4. Quebec also announced what's believed to be the province's first case of B1617 in the MauricieCentre-du-Qubec region.

On Thursday, Alberta reported its first case of the variant, which health officials said was in a returning interprovincial traveller.

On Friday, Ontario health officials confirmed that a total of 36 B1617caseshave been detected in the province, all of which were identified in the last few days.

Why are some people calling it a 'double mutant'?

The new variant has two mutations in the spike protein that the virus uses to fasten itself to a human cell's receptors and gain entry into the cell, which is where the term "double mutant" comes in.

Some experts saytheterm is a bit of a misnomer that doesn't by itself mean the variant ismore infectious or more lethal.

"The reality is many of the other variants of interest and variants of concern already have demonstrated multiple coexisting mutations so this concept of a double mutant to me is not a very helpful one," Dr. Andrew Simor, an infectious disease specialist at Sunnybrook Hospital in Toronto, told CBC News.

The two mutations the new variant carries, E484Q and L452R, have both been found separately in other coronavirus variants, but thisvariant is the first time they have been found together.

What has caught scientists' attention is that the E484Qmutation is very closely related to another mutation seen in the variants of concern first detected inSouth Africa and Brazil, while the L452R mutation has been noted in two variantsfirst detected in California that are also thought to be more transmissible.

Is this variant more contagious?

Becausesample testing has been limited, scientists have not established definitively how the combination of the two mutations affects how infectious the new variant is.

Dr. Cora Constantinescu of the Alberta Children's Hospital in Calgary saysthe variant seems to be more transmissible by at least around 20 per cent.

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A new variant of interest, first detected in India, contains two mutations of the coronavirus. These mutations make it more transmissible and more likely to avoid some antibody responses, says Dr. Cora Constantinescu of the Alberta Children's Hospital in Calgary.

While the virus does seem to account for more and more of India's caseload,other factors in the country may be contributing to its rapid spread there, Dr. Zain Chagla, an infectious disease expert with McMaster University in Hamilton, Ont., told The Canadian Press.

He cited the country's densely populated urban centres and multi-generational homes with poorly ventilated spaces.

"Is it because of situations that lead to high levels of transmission and super spreading, or is there something biologically different about this variant?" Chagla said. "Or is it some combination of the two?"

Will vaccines work against this virus?

While data is limited, Dr. Alain Lamarre, an immunologist and virologist with the Institut national de la recherche scientifique (INRS) in Quebec City, says the two mutations present in B1617 have been associated with a poorer antibody response.

That means the antibodies developed through a vaccine or a previous COVID-19 infection are less effective at neutralizing the new version of the disease, he said.

However, whether the vaccine failed to protect against the variant or the person had a particularly weak immune system is still unknown, he said.

It is also important to note thatantibodies aren't the only weapon our immune systems have to fight variants. For example,T cells are another tool our bodiesuseto help fight infection.

Dr. Ravi Gupta, who studies viruses at the University of Cambridge in England, says people should remember that vaccines and natural infectionstriggera whole range of different immune responses,and "these mutations only take away a fraction of our defences."

"Even though [the vaccines] may not stop us getting infection, they will stop us getting severe disease and dying from this disease, which is the critical thing."

Why is Canada banning flights from India now?

On Thursday, Canada imposed a 30-day ban on direct passenger flights from India and Pakistan in response to what federal officials said was a rising number of travellers from both countries arriving with COVID-19.

Health Minister Patty Hajdu said that while only 1.8 per cent of all air travellers entering Canada are testing positive, federal data show people travelling from India made up 50 per cent of all positive tests despite the fact that Indian travellers account for only 20 per cent of travel to this country.

When questioned on Power & Politics on why the ban wasn't implementedsooner, Transport Minister Omar Alghabra said Ottawa started seeing "alarming data" on positive tests being linked back to flights from India in the "last day or so."

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Transport Minister Omar Alghabra says Ottawa started seeing "alarming data" on positive tests being linked back to flights from India in the "last day or so."

However, some experts say a flight ban may be too late at this point when it comes to curbing the spread of the variant.

"I don't think it's going to make a huge difference if we have a travel ban," said Ananya Tina Banerjee, assistant professor in global health at Montreal's McGill University, on Thursday, just hours before the restrictions were announced.

"It's arrived here; we need to now focus on just mitigating the spread."

Like Banerjee, Simor said he believes it's a mistake to single out any one country or any one part of the world because variants have already spread into many different areas.

"The most effective thing is screening on arrival and in particular, quarantine on arrival," he said.