Thousands of homes in England will be visited by test teams to track the spread of the South African variant of the coronavirus.
About 80,000 people will be tested over the next few days as authorities vow to “come down hard” on the new strain.
Why has the UK brought in surge testing?
Public Health England identified 11 cases of the South African strain over the past week in people who had no known links to overseas travel.
Earlier, the UK had 105 cases of the new variant, but all of those cases were people who had recently been to South Africa, or had close contact with people who had.
The 11 unexplained cases have raised fears that the South African strain may be in community transmission in the UK.
Health Secretary Matt Hancock said the UK would “need to come down on it hard” before the new strain spiralled out of control, undoing the the recent reduction in daily cases.
How were the 11 cases identified and could there be more?
Public Health England used genome sequencing to determine the origin of the virus.
Between 5 and 10 per cent of all positive coronavirus tests were studied over the past week to determine the spread of the variant identified in South Africa.
Prof Nick Loman, from the Institute of Microbiology and Infection at the University of Birmingham, said he expected more cases of the strain to be found in the UK.
“It’s almost inevitable that a small fraction of people will transmit and sometimes those outbreaks can get pretty big, and the idea is to try and suppress that,” Prof Loman told BBC Radio 4.
What areas are affected?
The surge testing will take place in eight post codes across England.
They are Hanwell in west London, Tottenham in north London, Mitcham in south London, Walsall in West Midlands, Broxbourne in Hertfordshire, Maidstone in Kent, Woking in Surrey and Southport in Merseyside.
How will the tests be carried out?
Door-to-door testing will take place in some areas, with test kits pushed through the mailbox for collection later in the day.
Police officers and firefighters are being used as part of the campaign.
Other areas have brought in mobile testing units with residents urged to come forward regardless of whether they have symptoms.
Do vaccines work against the South African variant?
Scientists are concerned that the current vaccines may be less effective against the South African variant than the original strain.
Prof Loman said there was evidence to suggest the South African strain was resistant to existing antibodies, meaning somebody who was infected earlier might not be immune to the new strain.
Novavax and Johnson & Johnson’s vaccine was also less effective against the South African strain.
The vaccine was 85 per cent effective against the UK strain, but that dropped below 60 per cent in the South African trials.
Prof Calum Semple from the University of Liverpool said the UK needed to guard the vaccines from the South African variant.
“It's incredibly important to snuff it out when you can and seek it out when you can, and use that time of suppression to maximise vaccination,” Prof Semple said.
