There are now 3,424 cases of the Indian variant in the UK, according to the latest figures from Public Health England (PHE).
The B.1.617.2 variant of concern, which is believed to be more transmissible than the Kent variant that had become dominant in the country, has resulted in surge testing and vaccinations in many areas.
Health Secretary Matt Hancock said on Wednesday that 2,967 cases of the COVID-19 variant had been recorded, having stood at more than 2,300 on Monday.
These latest figures are up to 19 May and represent a rise of 2,111 from the previous week.
A total of 3,245 cases have been recorded in England, 136 in Scotland, 28 in Wales and 15 in Northern Ireland.
PHE said most cases are concentrated in the North West and London, but it was seeing "clusters of cases" across the country.
Dr Meera Chand, PHE’s COVID-19 incident director, said it was vital that people in the worst-affected areas who had yet to be given their second vaccine dose came forward as soon as it was offered.
"This is vitally important in the light of our current assessment that (B1617.2) has grown rapidly in England and may be highly transmissible," she said.
"PHE will continue to monitor all variants closely, paying particular attention to the impact on hospitalisations and deaths which will help us to understand the protective effects of the vaccine."
The spread of the variant has raised fears that England’s roadmap out of COVID restrictions could be delayed, but a postponement of step four, due on 21 June, is far from certain at this stage.
Boris Johnson has said there is "increasing confidence" that the current coronavirus vaccines will be effective against all variants, including the Indian one.
More than 37 million people have now had their first dose and 21 million have had their second, latest figures show.
The PM said earlier this week there was "nothing conclusive" at this stage to say step four of the roadmap – lifting all legal limits on social contact – could be pushed back.
Mr Johnson said "we will know a lot more in a few days’ time" and promised to "keep people informed" and "continually updated".
The expectation is that a clearer picture of how much more transmissible the variant is will emerge next week as more data is collected.
Speaking at a Downing Street news conference on Wednesday, Professor Jonathan Van-Tam suggested it may end up being less transmissible than first feared.
Professor Van-Tam, one of England’s deputy chief medical officers, said: "We have a credible range that goes from a few percent more transmissible through to 50% more transmissible – I think most people feel it is going to be somewhere in the middle… but it is just too early."