inclusion criteria: virology plymerase chain reaction (pcr) positive laboratory diagnosis of covid-19, within 6 months of diagnosis, persistent symptoms for at least 4 weeks from symptoms onset (groups a & b only) presentation type - one of group a, b or c;

inclusion criteria: virology plymerase chain reaction (pcr) positive laboratory diagnosis of covid-19, within 6 months of diagnosis, persistent symptoms for at least 4 weeks from symptoms onset (groups a & b only) presentation type - one of group a, b or c;

inclusion criteria: 1. virology plymerase chain reaction (pcr) positive laboratory diagnosis of covid-19, 2. within 6 months of diagnosis, 3. persistent symptoms for at least 4 weeks from symptoms onset (groups a & b only) 4. presentation type - one of group a, b or c;

inclusion criteria: 1. virology plymerase chain reaction (pcr) positive laboratory diagnosis of covid-19, 2. within 6 months of diagnosis, 3. persistent symptoms for at least 4 weeks from symptoms onset (groups a & b only) 4. presentation type - one of group a, b or c;