The Rockets were forced to cancel their scheduled opener Wednesday against Oklahoma City after being unable to field the minimum eight players, due in part to Harden.
But their official NBA injury report Friday revealed rookie forward Kenyon Martin Jr. and reserve Ben McLemore were self-isolating after testing positive for Covid-19.
Rockets center DeMarcus Cousins and guards John Wall, Eric Gordon and Mason Jones were listed as out due to "health and safety protocols," as they must quarantine after being declared close contacts to those with the deadly virus.
That leaves the Rockets nine players able to make the road trip to face the Trail Blazers.
Harden could not play on Wednesday after he violated NBA health and safety protocols that ban players from attending gatherings of more than 15 people.
The 31-year-old was fined $50,000 for attending an indoor party Monday, and team medical personnel required him to quarantine for four days and test negative for Covid-19 each day before clearing him to return to activities with the team.
The 2018 NBA Most Valuable Player has asked to be traded to one of several rival teams, expressing his unhappiness and remaining in Houston.