The positive results had been returned the previous day and the players were already been isolating at home.
The club has not communicated how long the two players will have to isolate or when they will be expected back in training.
However, both will miss Monday's (AEDT) trip to Cadiz and are unlikely to face Celta Vigo a week on Tuesday (AEDT).
While losing two important players will undoubtedly be a blow to head coach Diego Simeone, his side is sitting pretty at LaLiga's summit, and Real Madrid's defeat to Levante on Sunday (AEDT) added further comfort to Simeone's position.
Atleti has won seven in a row in the league and sits 10 points clear of Madrid at the top of the table.
Both Hermoso and Carrasco have played 15 out of Atletico's 18 LaLiga matches this term.