[theold]

ART can test negative. But if conduct PCR test, it is more accurate. Even those who got Covid can get Negative ART test later when recovered. But the PCR test can still be positive. 

So far cannot find any answer for how long those recovered from Covid can test negative for PCR test. The only clue is that the loss of senses like smell and taste are still there.

That might be the reason why most of the airlines required a PCR test.