After the latest round of testing at the Premier League runners-up, every player and member of staff received results back which indicated that the duo had indeed been infected.
They will now have to quarantine for two weeks in line with UK government guidelines.
Man City broke the news via a statement in their official website which read:
"Both players are currently observing a period of self-isolation in accordance with Premier League and UK Government protocol on quarantine. Neither is displaying symptoms of the virus.
"Everyone at the Club wishes Riyad and Aymeric a speedy recovery ahead of their return to training and the new season."
Man City were due to start their Premier League season this Saturday against Aston Villa, but have been given an extra week's rest compared to other clubs due to featuring in the latter stages of the Champions League tournament in Lisbon.
Should Laporte and Mahrez quarantine for two weeks they could return in time for the game against Aston Villa on 21 September. However, there will be concerns about match fitness and tactical preparations from Pep Guardiola for the pair as they will now be away from their team-mates for 14 days.
According to Goal, Guardiola himself is currently observing quarantine after returning home from Spain.