The patients were among more than 3,100 people tested in Chi Tai House at On Tai Estate, and Lai Tong House of Lai Tsui Court.
Of the preliminary positive cases, 136 came from On Tai Estate, and 105 from Lai Tsui Court.
The government said it will distribute disinfection products and surgical masks to them as they wait for follow-up arrangements.
Results for seven people were uncertain and health officials said these cases will be followed up accordingly.
Officers also visited more than 1,300 households of the two buildings, among which 113 households did not answer the door.
The tests had been ordered after sewage samples in the areas tested positive for the coronavirus.