It comes after a five-day 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 it was likely the person completed a home test on 12 or 13 February but failed to fill in their registration card.
The search was “narrowed down to 379 households in the southeast” earlier this week but reports on Friday said that the individual has now been located.
Public Health England worked with postal and courier services to determine where the test was originally sent from.
The precise location has not been revealed, and nor has the identity of the missing person.