This is similar to some of the reports from China and South Korea, where people seem to recover fully and then come down with symptoms again. The Roosevelt had 970 cases in the first round, and now 13 have relapsed.
https://www.npr.org/sections/corona...velt-sailors-test-positive-for-covid-19-again
https://www.npr.org/sections/corona...velt-sailors-test-positive-for-covid-19-again
The U.S. Navy says 13 sailors from the USS Theodore Roosevelt who had apparently recovered from the coronavirus and had received negative test results have now tested positive for a second time.
...
the Navy said the sailors had "met rigorous recovery criteria, exceeding CDC guidelines," including testing negative for the virus at least twice, but have now retested positive.
...
"These five Sailors developed influenza-like illness symptoms and did the right thing reporting to medical for evaluation," the statement said.
The Navy has since confirmed to NPR that an additional eight sailors have retested positive for coronavirus, bringing the total to 13.