LB-DTK-COV19

The goal of this clinical study is to evaluate the safety and efficacy of autologous COVID-19 antigen specific T cell (LB-DTK-COV19) treatment in prolonged SARS-CoV-2 infected patients. The main questions it aims to answer are:
* What adverse events occur after the infusion of LB-DTK-COV19?
* Is there a clinically significant improvement in clinical symptoms within 4 weeks after the infusion?
* Is there a clinically significant reduction in SARS-CoV-2 viral load within 4 weeks after the infusion?
The patients will:
* Receive a single infusion of LB-DTK-COV19 either intravenously or using central venous catheter during the baseline visit at a dose of 1x10^7/m^2.
* Receive a second infusion of LB-DTK-COV19 either intravenously or using central venous catheter at the same dose 14 days after the first infusion.
* Attend follow-up visits at the clinic for 6 months after the first infusion.