The median R0 = 5.7 indicating that COVID-19 is highly infectious; each infected person spreads it to 5-6 others.
COVID-19 was present many months before countries implemented lockdown measures, and because it is highly contagious, has spread to nearly everyone since November 2019.
Thus, contact tracing this far into the epidemic will prove fruitless because everyone has already been exposed.
No existing COVID-19 test will tell you who specifically is infectious, who is not infectious or who, including those who have already been exposed previously, will become infectious. Moreover, it is unknown how to use any such contact tracing data to reduce C19 transmission risk.
Because COVID-19 testing is highly imprecise, yielding both false positives and false negatives, it does not make sense to use Contact Tracing to track the C19 virus.