The club have called it "a serious error of judgement."
Dundalk have confirmed that their entire squad have since returned negative results from COVID-19 tests.
The Lilywhites' match against Finn Harps on Friday will go ahead as planned following consultation with the H-S-E.

Kildare County Council Honours Kildare Senior Football Team with Certificate of Recognition
Wednesday Morning Sports Update
Kildare’s Best Christmas Ho Ho Home Competition
Ireland's James Ryan Received First Career Red Card In Saturday's Game Against South Africa
RDS To Be Known As 'Laya-Arena' After Major Rebrand
Eadestown Tadgh Beirne Included In World's Rugby Team Of The Year
Tuesday Morning Sports Update
Irish Rugby Squad Face Multiple Injuries Woes Following Saturday's Game