The hunt for the missing case of the Brazil coronavirus variant in England 'should be easy', an expert has said as the Department of Health continues its scramble to find them.
A positive test from a home test kit done in mid-February was found to be the mutant P1 strain that officials are desperately trying to control.
But Test and Trace officials currently have no idea who the person is. They cannot be sure whether they had even travelled from Brazil and have only narrowed down their search to 379 homes in the South East.
Kent and Surrey councils told MailOnline they were not aware of efforts to track the case in their populations, ruling out a third of the region's 9million people.
Department of Health officials, who have worked alongside the Royal Mail to find the missing case, have refused to specify their search area.
Dr Simon Clarke, a microbiologist at the University of Reading, said that it should be 'easy' to find the person if they had travelled to Brazil before being diagnosed.
But there is no guarantee they did and the fact they didn't give contact details when they posted their swab test could mean they think they're in trouble and don't want to come forward, he said.
It is unlikely the person is still infected or able to spread the disease because the test was taken on February 12 or 13 and most people recover within a fortnight.
But health chiefs will want to track them down to quiz them on there whereabouts in the past month, to ensure the variant hasn't been spread further.
Health Secretary Matt Hancock yesterday gave the first hint officials were getting closer to tracking down the person, who was one of six confirmed cases with the Brazilian P1 variant.
The Government has found five out of the six confirmed cases caused by the P1 Brazilian variant but one, somewhere in the South East of England, has still not been identified
Health Secretary Matt Hancock yesterday said: 'Our search has narrowed from the whole country down to 379 households in the South East of England and we're contacting each one'
He said in the House of Commons: 'We've identified the batch of home test kits in question.
'Our search has narrowed from the whole country down to 379 households in the South East of England and we're contacting each one.'
Dr Clarke told MailOnline: '379 isn’t an awful lot, you’d think it would be very easy to look through and find someone who has been to Brazil.
'Asking a simple question of "have you been to Brazil recently" would rely on people telling the truth, of course.
'Someone who hasn’t filled in the form properly might think they’re in trouble... There’s been a lot of publicity around this and, had somebody made a mistake, then the likelihood is they would have put their hands up.'
There are concerns the efforts to find the person are going too slowly and beginning too late.
If someone has taken a test because they developed symptoms of coronavirus they likely caught the virus around five days earlier, because this is the average time it takes symptoms to develop.
STUDY FINDS BRAZIL VARIANT MAY REINFECT 2/3 PEOPLE WITH IMMUNITY
A study led by Imperial College London and published online yesterday has found that the Brazil variant of coronavirus may cause reinfection among 61 per cent of people who have already had Covid caused by a different strain.
Research on the P1 variant among people living in the Brazilian city of Manaus found potentially high levels of reinfection, and that the variant was more transmissible than the original pandemic strain.
British experts have cautioned that the study cannot be used to predict what may happen in the UK.
According to the new study, blood testing suggests more than 67 per cent of people in Manaus may have had Covid by October 2020.
There was surprise then when the city suffered another huge wave of coronavirus at the start of this year, so experts sought to find out why.
They found that the proportion of Covid cases that were the P1 variant grew from zero to 87 per cent in about eight weeks.
P1 was found to be 1.4 to 2.2 times more transmissible than other variants in Manaus, and was found to evade 25 per cent to 61 per cent of protective immunity from previous infection.
Dr Nuno Faria, reader in viral evolution at Imperial, told a briefing: 'If 100 people were infected in Manaus last year, somewhere between 25 and 61 of them are susceptible to reinfection with P1.'
The study could not say how severe illness was in people who were reinfected. It found a slightly higher death rate connected to P1 cases in Manaus but said this coincided with 'substantial healthcare failure' and hospitals running out of oxygen, so it couldn't be pinned on the new variant.
Coronavirus genetics expert at COG-UK, Professor Sharon Peacock, said the study could not be used to speculate on the effectiveness of vaccines or how things 'will pan out in other countries including the UK'.
And if they caught it abroad or while travelling they may have passed a lot of people, increasing the risk of them passing it on.
Labour's shadow health secretary Jonathan Ashworth slammed the Government's efforts yesterday and said: 'I welcome the progress the Secretary of State has mentioned on identifying the batch, but can he tell us how a test can be processed that doesn't collect contact details, and what mechanisms will be put in place to fix this in future?
'£22billion has been allocated to test and trace so can he assure us this won’t happen again?
'I note he has said there is no information to suggest wider spread of the variant but he will remember that John Edmunds from SAGE told the Home Affairs Select Committee in January that for every identified South African variant there were probably another 30 unidentified.
'Has he received any estimate on the numbers of unidentified cases there are in the community?'
The fact that the country is in lockdown and the reproduction number (R) of the virus is below one means it is unlikely the person passed the virus on to a stranger.
But there is a possibility people in their household may have caught it. When they are identified more detailed contact tracing will have to be done, potentially retracing their steps for multiple weeks.
But Dr Clarke said the person was not likely to still be capable of spreading Covid, adding: 'Even if it was an old person, the chances are they didn’t get particularly ill and resolved the infection... The chances are that person no longer has the virus.'
In total, Public Health England has identified six UK cases of the concerning so-called P1 variant – three in England and three in Scotland.
Three cases are Scottish residents who flew to Aberdeen from Brazil via Paris and London, who all tested positive while self-isolating.
Other passengers who were on the same flight to Aberdeen are now being traced.
The other two cases in England are from the same household in South Gloucestershire after one person returned from Brazil on February 10 – just days before the Government's hotel quarantine rule came into force.
Two other people in the same household have also tested positive but are not currently included in the UK case total of six, while tests on their type of coronavirus continue.
Officials are searching for passengers who were on the Swiss Air flight LX318 from Sao Paulo to Heathrow, via Zurich, which landed on February 10.
Surge testing will now be carried out in the Bradley Stoke, Patchway and Little Stoke areas of South Gloucestershire to capture any potential spread in cases.
Labour leader Sir Keir Starmer said the discovery of the variant in the UK showed the Government had not 'secured our borders in the way we should have done'.
Vaccines minister Nadhim Zahawi said any community transmission of the variant would be identified 'very, very quickly' through both regular PCR and lateral flow testing.