Van Dijk, Fabinho and Jones all tested positive for Covid prior to the Newcastle clash on December 16, with government guidelines stipulating a seven-day quarantine.
The trio were then required to provide negative lateral flow tests on the sixth and seventh days of their self-isolation, which were on Wednesday and Thursday.
With none of their results returning positive, and no symptoms shown, they were then given the all-clear to return to Kirkby for training.
They were part of the group put through exercises on Christmas Eve, with Liverpool now able to extend their preparations for the trip to Leicester on December 28.
Due to a rise in cases in the Leeds squad, the Boxing Day clash at Anfield has now been postponed, at least allowing Klopp and his players more time to train for a second consecutive meeting with the Foxes.
In the festive spirit ?? pic.twitter.com/ujHXCL33DV
— Liverpool FC (@LFC) December 24, 2021
Ahead of Christmas Day, the first team posed for a photo on the pitch at Kirkby, with Van Dijk, Fabinho and Jones all present.
Jones could be given more time to get back up to speed, having not featured for Liverpool since the 2-2 draw with Brighton on October 30 due to an eye injury and then Covid.
Thiago remains absent, with his quarantine due to end on Boxing Day, while there was no sign of Joe Gomez, Naby Keita, James Milner or the injured quartet of Harvey Elliott, Divock Origi, Nat Phillips and Adrian.
However, there is an ongoing chance of players testing positive for Covid upon their arrival at the training ground, with negative lateral flow tests required before entry is granted.
Either way, Liverpool will consider the return of Van Dijk, Fabinho and Jones as a major boost, with no delay in their comeback due to the emergence of symptoms.
Liverpool squad in Christmas Eve training
Goalkeepers: Alisson, Kelleher, Pitaluga, Davies
Defenders: Van Dijk, Matip, Konate, Alexander-Arnold, Robertson, Tsimikas, Williams, Beck
Midfielders: Henderson, Fabinho, Oxlade-Chamberlain, Jones, Morton
Forwards: Salah, Mane, Firmino, Jota, Minamino