Health officials on Thursday confirmed the first local case of Covid-19 in nearly two months, though they said the man was probably infected some time ago.
The patient, a 43-year-old construction worker, tested weakly positive earlier this week. Tests run after he was hospitalised showed he was positive for antibodies.
The Centre for Health Protection said this case is compatible with a re-positive case previously undiagnosed.
There were also five imported cases involving people who returned from Ireland, Cambodia, the United States, Thailand and Russia.
Three of the patients carried the L452R mutant strain, while one of them was infected with the N501Y strain.