The case numbers related to the B1.617.2 variant of COVID-19, first identified in India, have more than doubled within a week in the UK, resulting in further surge testing and enhanced vaccine measures to be deployed in parts of the country where the strain is beginning to spread increasingly rapidly .

Public Health England (PHE) said on Thursday that its latest analysis shows the number of cases of the highly transmissible variant first detected in Maharashtra has risen from 520 last week to 1,313 cases this week.

Most cases are in the northwest of England, with some in London, and additional measures are being put in place to “rapidly break chains of transmission”.

UK Health Secretary Matt Hancock said the health authorities are monitoring the situation very carefully and will not hesitate to take further action if necessary, indicating that the roadmap to lifting all lockdown measures from June 21 may have to be reassessed.

This data demonstrates why our swift and decisive measures are in place. Everyone has a part to play in controlling this variant, from participating in surge testing, to following the rules, to getting the jab, said Hancock.

We are committed to working with local areas and deploying our world-leading genomic sequencing to get this variant under control. We are supporting areas where the cases of this variant are rising, he said.

The minister said it is imperative that people who live in one of the 15 areas currently covered by surge testing processes get a free PCR test and everyone who’s eligible needs to come forward and get their vaccine.

PHE said that while there is no firm evidence yet to show this variant has any greater impact on the severity of disease or that it evades vaccines, the “speed of growth is concerning”.

UK Vaccines Minister Nadhim Zahawi said the authorities are looking at how to best utilise the vaccine roll-out to protect the most vulnerable in the context of the current epidemiology, including the possibility of bringing forward the second doses for the most vulnerable in some of the most affected areas.

Andy Burnham, the Mayor of Manchester, one of the hotspots of the variant, has also called for a speeding up in the age eligibility criteria for vaccines in the affected areas. The National Health Service (NHS) is now offering a jab to all over the age of 38.

Cases of this variant are rising in the community and we are continuously monitoring its spread and severity to ensure we take rapid public health action, said Dr Susan Hopkins, COVID-19 Strategic Response Director at PHE.

Testing and isolating when required not only limits spread, it helps us to better understand how the variant behaves in the community which is vital to taking effective and proportionate action moving forward

“The way to limit the spread of all variants is the same. Keep your distance, wash your hands regularly and thoroughly, cover your nose and mouth when inside, keep buildings well ventilated and meet people from other households outside, she said.

The variant was confirmed as a “Variant of Concern” by PHE on May 7 after a rise in cases and evidence of spread in some areas. Since then across the northwest of England, significant work is underway with local councils and partners.

In Bolton, mobile testing units have been deployed and door to door PCR testing has been offered to 22,000 residents. A vaccine bus has been established in the heart of the community to increase vaccine uptake as part of a wider drive.

PCR testing, whole genome sequencing and enhanced contact tracing are being used throughout London to target the many small dispersed clusters. All positive tests in London with a high enough viral load are also being prioritised for genomic sequencing to check for variants, and surge testing can begin immediately if it is needed.

Taking this community-led approach has already proved effective in reducing transmission of variants in London to date, PHE said.

To help identify variant cases, surge testing is being deployed in 15 areas across England to suppress transmission, with more than 800,000 additional PCR test kits distributed.

According to the Department of Health and Social Care (DHSC), over 4,400 cases and over 14,000 close contacts have been traced and instructed to self-isolate.

Over 200 existing test sites and 130 schools have distributed test kits, with Mobile Testing Units deployed to provide PCR testing for people without symptoms.

The public is also being urged to continue to take up the offer of two free rapid tests a week, to help identify asymptomatic cases. Anyone who does test positive in this way should take a follow-up PCR test, which can be sent for genome sequencing to help catch new variant cases.