While the Portuguese star was on international duty he tested positive for the virus and subsequently had to isolate.
So far he has missed three Juventus games - Crotone and Verona in Serie A, and the Champions League group stage opener versus Dynamo Kyiv a week ago.
Ronaldo was in line to make his return this Wednesday when Juve host Barca at the Allianz Stadium, but only if he could successfully record a negative coronavirus test on Tuesday the day before the match.
He failed, with the results showing he is still positive, which has left Juve without their star man against for their biggest game of the season so far.
The 35-year-old insists he is feeling fine, however, and has blasted the current testing as ineffective due to his lack of symptoms.
The typical coronavirus test is known as PCR which stands for Polymerase Chain Reaction.
Ronaldo let his followers know his feelings via a couple of posts on Twitter and Instagram: