Andrew Hayward, professor of infectious disease epidemiology at University College London – who is also a member of Sage and the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) – said Britain should “err on the side of caution” when deciding whether or not to place India on the “red list” for travel.

He told BBC Radio 4’s Today Programme: “The evidence of increased transmissibility and escape from immunity is circumstantial.

“That said, it’s going to take a number of weeks at least before that evidence gets firmed up and we find out more.

“Certainly some countries and areas have taken the view that that’s enough for them to be quite concerned – so for example, Hong Kong has put on a two-week travel ban, which will allow them to find out a little bit more.” He said it was about weighing up the harms and benefits of putting India on the travel ban list.

He said: “…The challenge with that is that the level of harm is quite high because we’re highly connected with India – there’s a lot of economic interaction as well as family and social interaction.

“And on the other hand, what we have is an unknown level of risk – my own preference in all of this is to err on the side of caution and to act sooner rather than later. But ultimately, that’s going to be a political decision.”

Ontario, Canada’s most popular province, will start offering the AstraZeneca vaccine to those aged 40 and older amid a third wave of the virus, an exclusive report by Reuters said.

The vaccine was previously only being offered to over-55s after a review by Canada’s National Advisory Committee on Immunisation (NACI) recommended the jab not be used in people under the age of 55 due to blood clot concerns.

NACI’s recommendation is not binding and Health Canada, the country’s drug regulator, has said it will not restrict the use of the AstraZeneca vaccine because the benefits outweigh potential risks.

The change is set to be announced today and enforced on Tuesday, Reuters said.

Boris Johnson is under increasing pressure to cancel his planned trade trip to India later this month as cases of Covid-19 in the country soar.

Opposition parties have lined up to urge the prime minister to put off the trip, as calls mount for India to be placed on the government’s travel “red list”.

Our Whitehall Editor Kate Devlin and my colleague Joanna Taylor report:

Danny Altmann, professor of immunology at Imperial College London, said he expects that the Indian variant of the virus which causes Covid-19 will become a “variant of concern”, which would lead to India being placed on the government’s “red list” of hotel quarantine countries.

He told Good Morning Britain: “I am concerned about all the variants.

“I think our road map is going well and at the moment, in this country, we are doing rather well, enjoying unlocking – but out there there is the Indian variant, the South African, Brazilian etc, and they do pose a threat.”

He said that some people in the population are still vulnerable who can “still be caught out by variants like this”.

Prof Altmann added: “At the moment, this particular variant (from India) is called a variant under investigation, not a variant of concern because it hasn’t been escalated to that level yet.

“My assumption from everything I’ve seen is that it will become a variant of concern.

“When it becomes a variant of concern, I’d be quite surprised if India wasn’t on the red list.”

Volunteers who have recovered from a coronavirus infection will be deliberately infected with the virus for a second time, in a new study that could help develop new treatments and vaccines agains the disease.

The study, led by a team from the University of Oxford, will investigate how a previous infection affects a second exposure to the virus and what kind of immune response is needed to protect people.

Our Health Correspondent Shaun Lintern has more:

Good morning and welcome to The Independent’s liveblog, bringing you the latest updates in the coronavirus pandemic.