Celtic confirmed on Monday that manager Neil Lennon and 13 senior players are self-isolating, but the club are still defending the decision to hold a training camp in Dubai.
Defender Christopher Jullien tested positive for COVID-19 after the team returned to Scotland ahead of Monday's Premiership clash with Hibernian.
Although all other squad and staff members returned negative tests, Lennon, assistant John Kennedy and 13 first-team players are self-isolating after being deemed close contacts.
The reigning champions remain insistent they followed "rigorous" COVID-secure protocols and that the threat of contracting the virus would have been similarly high had they stayed in Scotland.
In a statement, Celtic said: "Clearly we are hugely disappointed, as we know our supporters will be. The contacts were identified during the period from Wednesday last week, primarily around flight and team coach travel, during which time Celtic applied the same rigorous protocols used for pre-season training camps, UEFA match travel and for all domestic match arrangements in Scotland.
"These protocols have served us well in the past, as the club has not had one positive case in our own 'bubble' until now. As we have already stated, Celtic's decision to travel to Dubai for a training camp was for performance reasons. Whilst we were in Dubai, the announcements made on January 4 significantly changed the COVID landscape.
"The reality is that a case could well have occurred had the team remained in Scotland, as other cases have done in Scottish football and across UK sport in the past week.
"Celtic has done everything it can to ensure we have in place the very best procedures and protocols. From the outset of the pandemic, Celtic has worked closely with the Scottish Government and Scottish football and we will continue to do so."
The Hoops' latest Scottish Premiership outing will go ahead as planned despite the Covid-19 outbreak within Lennon's squad, with Celtic in desperate need of a victory after losing to arch-rivals Rangers last time out.
A 1-0 defeat against the Gers at Ibrox saw the reigning champions fall 23 points behind in this season's title race, but they do still have four games in hand to take in on Steven Gerrard's side.
After their meeting with Hibs, Celtic will look ahead to a doubleheader against Livingston, with the teams set to meet on January 16 at Parkhead before doing battle again at Almondvale Stadium four days later.