The four women and two men, aged between 37 and 50, arrived from the United States, Britain, the Philippines and Tanzania.
All of them were vaccinated earlier and tested positive for the potentially more contagious L452R mutant strain after arriving in Hong Kong.
One of the patients was a flight crew member from Britain. The 50-year-old woman flew in on Sunday and was asymptomatic.
Two patients were domestic helpers from the Philippines, with one of them undergoing quarantine at the Best Western Plus Hotel in Sai Ying Pun when her infection was confirmed.