Health authorities said the fully-vaccinated patients – a 33-year-old woman and 55-year-old man – flew in from the Philippines and South Korea respectively.
They were asymptomatic, and tested positive for the L452R mutant strain.
Officials said the male patient lives at Amber Garden in Happy Valley, and travelled to the US on August 18. He tested negative before his departure.
He last went to work at Tesbury Centre in Wan Chai on August 17.
Authorities announced earlier that people who had been to these two places must take a Covid test.