This is an issue with PCR tests, but not Rapid Antigen Tests (RATs). PCR tests can return a positive result during the period when individuals have recovered and are non-infectious, but could be shedding the virus from their system. RATs don’t track the virus, but rather, the body’s reaction to it (antigens) so RATs performed after recovering from infection won’t produce a positive response to shedding. SA Health advice on isolation and recovery can be found here