The 24-year-old played the full match on Sunday evening when the Giallorossi thrashed Benevento 5-2 but he was suspended for their 2-1 victory against Young Boys in the Europa League on Thursday night.
Even if he was not suspended, he would not have been available anyway and he revealed on social media that he had contracted the virus.
“Hello everybody, I have tested positive for COVID-19 and as a consequence I have decided to quarantine,” Mancini said on Instagram.
“Fortunately I feel good and I am already counting down to when I return onto the pitch. See you soon and forza Roma!”
Mancini joined from Atalanta in the summer of 2019 and he has played 45 competitive matches so far for the Giallorossi.