Cologne have announced three people at the club have tested positive for coronavirus – yet training will continue ahead of the Bundesliga's return.
The German top flight looks set to become the first major league to return to action as the world continues to deal with the Covid-19 pandemic.
Clubs are back in training with a mid-May resumption on the cards, but Cologne's arrangements have received a setback.
The club, 10th in the Bundesliga, said that "after three positive tests, three people at FC Koln are now in quarantine" – but also that "the group training can continue".
In a statement, Cologne said: "FC Koln had the entire team and coaching staff, along with the backroom staff, tested on Thursday for Covid-19. Three people tested positive, all are symptom free.
"After an assessment of the cases by the responsible health authorities, the three people who tested positive will go into a 14-day quarantine at home. FC Koln will not confirm any names out of respect for the privacy of those affected.
"FC Koln's training can continue as planned, according to the hygiene and infection control measures that have been in place since April 6 in group training.
"The prerequisite for this is that the relevant group of people are tested further, as stated for in the medical concept of the 'Taskforce Sports Medicine/Special Game Operation' from the DFL."
The procedure discussed on Friday with the taskforce's chair Professor Dr Tim Meyer, medical director of the Institute for Sports and Preventive Medicine at Saarland University, and Professor Dr Barbara Gartner, specialist in microbiology and infection epidemiology.
Meyer said: "We now see in everyday life that our concept recognises and reduces risks at an early stage.
"We will always be in close contact with the responsible health authorities and medical experts.
"We are convinced that with our concept, we can enable players to practice their profession with the best possible protection against infection."
Cologne managing director Horst Heldt: "The health and private sphere of players and staff have priority above all else.
"The previous measures, as well as the strategy of regular tests, have proven themselves so that we can now react with individual solutions."
