The Centre for Health Protection said the two men, arriving from Switzerland and the United States, had received both doses of the BioNTech vaccine in Hong Kong between March and May.
It said the two, aged 54 and 44, carried the L452R mutant strain but were both asymptomatic
There were also fewer than five preliminary positive cases.
The centre was also notified by authorities in the UK and Japan that two men who flew there from Hong Kong earlier this month had tested positive for Covid-19.
One of them stayed at Tower 5, Phase 3 of The Graces, Providence Bay and the Gateway Hotel before he left Hong Kong.
People who visited these premises have been ordered to get tested for Covid-19.