Champions League winner Joshua Kimmich, who has been at the center of a high-profile row after refusing to take a Covid vaccine, has been ruled out until 2022.
Bayern Munich star Kimmich is arguably the best-known player to have made it publicly clear that they have not been vaccinated.
The Germany midfielder said he had "concerns about the lack of long-term studies" on Covid vaccines when he confirmed the news in October.
That has become part of an escalating row in Germany, with Bayern thought to be unimpressed and ready to dock Kimmich's mammoth pay packet under rules in the country that do not guarantee wages to employees who miss work and are unvaccinated.
Germany boss Hansi Flick, who had to make do without Kimmich after he was one of several players deemed a close contact to a squad member who tested positive, has insisted that the 26-year-old is not a "Covid denier" or a conspiracy theorist – claims that are often leveled at the unjabbed.
Ex-Liverpool powerhouse Dietmar Hamann has said that it "cannot be that Kimmich continues to receive his salary”, and Bayer Leverkusen supremo Rudi Voller – a former World Cup winner with Die Mannschaft – recently warned that the unvaccinated are "indecent" and "must bear the consequences".
Now some fans are worried for Kimmich's long-term health after the Bundesliga champions announced that he is out with a lung problem just two weeks after testing positive for Covid.
“I’m doing fine but due to slight infiltrations in the lung, I’m not able to be back in full training currently," Kimmich is quoted as saying.
"So I’ll undergo rehab training and can hardly wait to be back completely in January.”
Speaking after football returned to major leagues across Europe following widespread lockdowns in 2020, Dr Flaminia Ronca, a sports scientist at an International Olympic Committee research center in London, spoke about the tests that clubs would likely be carrying out on top stars.
"If there is a hint that there might still be some inflammation or an issue with the heart or lungs, they need further examination because the risk of myocarditis, blood clots or lung damage are the biggest worries," Ronca told The Athletic.
"Endurance elite athletes are particularly susceptible to airways diseases, and some athletes have reported suffering a wheezing sensation after Covid-19 symptoms have subsided, and we need to investigate that.
"When monitoring, we would carry out a series of lung-function tests, ranging from simple spirometry up to a CT scan in the most severe cases."
Ronca added that "anything is possible" in terms of the damage Covid could cause to the lungs of top athletes.
Shortly after Ronca spoke, French rugby club Stade Francais announced the cancelation of a pre-season friendly because some of their players developed lesions on their lungs after contracting Covid.
Supporters speculated that Kimmich may be facing a similar issue. His absence is also a major blow to Bayern, who have few obvious alternatives to fulfil his role in their team.
Julian Nagelsmann's side qualified for the Champions League knockout stage in style on Wednesday, completing six wins out of six in the group stage by ousting Barcelona from the competition with a 3-0 home win.
The match was played in front of an empty Allianz Arena under Covid restrictions in place in Germany.