As I understand it, all of them (at least at Cofidis) had texted negative. But the problem is that it takes several days to get the test results, and by that time several riders had suspicious symptoms, so they had to start all over again. They had to retest not only the sick riders, but everyone else, since if one or more of the riders had the virus,it's possible others did, too, even without showing symptoms. But if the quarantine was tight, and everyone was originally negative, no one should have subsequently tested positive. It's possible there was a false negative, but it seems more likely to me that either someone picked up the virus from someone or something at the hotel, or that the sick riders are not in fact suffering from COVID-19.
In theory, this could go on indefinitely, because if one or more riders is positive, it's possible that he exposed the virus to someone else during the period in which the latest tests were being carried out. Short of quarantining everyone separately, you can never rule out this possibility. The people on the Diamond Princess were in effect quarantined, tried to avoid each other as much as possible,and and look how that turned out.
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