Health secretary Matt Hancock told a Downing Street press conference that there was “no sign of any onward transmission” from the individual in question, who had recently returned from Brazil. “The best evidence is that this person stayed at home,” he said.
The missing person who tested positive for the Brazilian coronavirus variant has been located in Croydon, the government has said.
It comes after a five-day national hunt to track down the individual, one of six people in the UK to have been infected with the variant, known as P1.
Authorities said the person completed a home test on 12 or 13 February but failed to properly complete their online registration form.
The search was “narrowed down to 379 households” earlier this week but the government confirmed on Friday that the individual has now been located in Croydon.
Public Health England (PHE) worked with postal and courier services to determine where the test “may have been sent from and to”.
Nonetheless, targeted testing has been introduced to parts of Croydon “as a precaution”, Mr Hancock added, to “minimise the possibility of spread”.
The revelation that authorities had initially failed to identify one of six people infected with P1 sparked widespread criticism of the government’s border controls.
According to the data, the first cases were probably imported to the UK just days before mandatory hotel quarantine was enforced for arrivals from “red list” countries.
Nick Thomas-Symonds, the shadow home secretary, said: “This is further proof that the delay in introducing a hotel quarantine was reckless and the continuing refusal to put in place a comprehensive system leaves us exposed to mutations coming from overseas.”
However, Mr Hancock said: “Incidents like this are rare and only occur in around 0.1 per cent of tests.”
The P1 variant is estimated to be roughly twice as infectious as other mutated forms of the virus and can partially evade immunity elicited by previous infection.
A study into people infected with P1 in the Amazonas city of Manaus showed that the variant carries a “unique constellation of mutations”, which makes it between 1.4 and 2.2 times more transmissible. The research has not yet been peer reviewed.
It is also “able to evade 25-61 per cent of protective immunity” caused by previous infection with other variants, according to the research.
Experts cautioned that the findings cannot be used to predict what may happen in the UK.
P1 has been associated with a large second wave of infections that ripped through Manaus in late 2020 and early January. This is despite previously high levels of immunity in the local population, with 67 per cent of people estimated to have been exposed to coronavirus by October last year.
The variant carries the E484K mutation in its spike protein – the part of the virus responsible for attaching to human cells – and is therefore capable of partially evading the body’s neutralising antibodies.
P1 also has the same N501Y mutation seen in the highly transmissible UK variant.
Although it’s suspected P1 could diminish the effectiveness of the current generation of Covid-19 vaccines, studies have suggested jabs will continue to provide protection against severe illness, hospitalisation and death, regardless of the variant that has caused the infection.