Travel from India to the UK is being banned for non-UK and non-Irish citizens from 4am on Friday after the country was added to the travel “red list”.
The so-called India variant is known as a double mutant as it has two new significant mutations in the spike protein of the virus that help it infect cells and evade the immune system.
According to figures from the COVID-19 Genomics UK Consortium (COG-UK), which tracks COVID variants, 182 cases of the India variant have so far been found in the UK up to 16 April.
Of those, 162 cases have been found in the last five weeks.
In a statement to the House of Commons on Monday, Mr Hancock told MPs: “We’ve been analysing samples from these cases to see if this variant has any concerning characteristics – like greater transmissibility or resistance to treatments and vaccines – meaning it has to be treated as a variant of concern.
“After studying the data and on a precautionary basis, we’ve made the difficult but vital decision to add India to the red list.”
The health secretary said the “vast majority” of cases of the India variant are linked to international travel and have been picked up by border testing.
Mr Hancock’s announcement applies to travel from India to England, although it is likely the devolved governments in Scotland, Wales and Northern Ireland will introduce similar measures.
The decision to place India on the travel “red list” means anyone who is not a UK or Irish resident or a British citizen cannot enter England if they’ve been in India in the previous 10 days.
And, for those UK and Irish residents and British citizens who have been in India in the past 10 days, they will have to complete a 10-day hotel quarantine period on their arrival in the UK.
The rules will come into force from 4am on Friday.
He added: “India is a country I know well and love. Between our two countries we have ties of friendship and family.
“I understand the impact of this decision, but I hope the House will concur we must act because we must protect the progress we have made in this country in tackling this awful disease.”
The health secretary was unable to confirm whether the UK’s existing vaccines would be effective against the India variant, telling MPs: “We simply don’t know that.”
“Of course we’re looking into that question as fast as possible but that is the core of my concern about the variant first found in India, is that the vaccines may be less effective in terms of transmission and, or in terms of reducing hospitalisation and death,” he added.
“It is the same concern that we have with the variant first found in South Africa and is the core reason why we took the decision today.”
But Mr Hancock reassured MPs that the government was “ramping up plans for a booster shot to make sure our vaccines stay ahead of the virus”.
He said work was being carried out to assess which vaccines will be effective in targeting “variants of concern”, such as the one first found in South Africa.
The addition of India will mean there will be 40 countries on the UK’s travel “red list”. These include large parts of southern Africa and the entirety of South America.
Earlier this month, Bangladesh, Pakistan and the Philippines were also added.
Labour’s shadow health secretary Jonathan Ashworth welcomed the addition of India to the travel “red list”.
“I’m immensely proud of our deep ties and bonds to India, but we must always be vigilant, be driven by data and have zero tolerance for variants that could set us back,” he said.
Mr Ashworth highlighted how India currently has “one of the world’s steepest surges” in COVID cases, with the India variant of the disease now having become dominant in the Asian country over the past few weeks and “outcompeting our own homegrown Kent strain”.
He also noted the India variant had become “the fastest growing variant in the UK” in recent weeks and that the UK now had “cases in the community not linked to international travel”.
Mr Ashworth urged Mr Hancock to put in place surge testing to target the India variant, which the health secretary confirmed would happen.
Fellow Labour MP Yvette Cooper, the chair of the Commons’ home affairs committee, asked why India had not been put on the “red list” sooner.
“Hong Kong this week have identified 47 COVID cases just on a single Delhi flight and we have still 16 more direct flights, many more indirect flights from India to here before Friday alone,” she said.