Table 2. Clinical trials identified at Clinicaltrials.gov related to biological intervention for COVID-19 treatment.

Study	Study Start	Interventions	Severity	Target Number	Phase	Status	Country
Immunity and Safety of Covid-19 Synthetic Minigene Vaccine	24-Mar-20	LV-SMENP-DC vaccine + antigen-specific CTLs	Mild/Severe	100	I/II	Recruiting	China
A Phase I/II Study of Universal Off-the-shelf NKG2D-ACE2 CAR-NK Cells for Therapy of COVID-19	21-Mar-20	NK cells vs. IL15-NK cells vs. NKG2D CAR-NK cells vs. ACE2 CAR-NK cells vs. NKG2D-ACE2 CAR-NK cells	Mild/Severe	90	I/II	Recruiting	China
Treatment of COVID-19 Patients Using Wharton's Jelly-Mesenchymal Stem Cells	16-Mar-20	WJ-MSCs	Mild/Severe/ Critical	5	I	Recruiting	Jordan
Treatment With Mesenchymal Stem Cells for Severe Corona Virus Disease 2019 (COVID-19)	5-Mar-20	MSCs vs. control	Severe	90	1I/II	Recruiting	China
NK Cells Treatment for Novel Coronavirus Pneumonia	20-Feb-20	NK Cells vs. control	Mild/Severe/ Critical	30	I	Recruiting	China
Safety and Immunity of Covid-19 aAPC Vaccine	15-Feb-20	Pathogen-specific aAPC	Mild/Severe	100	I	Recruiting	China
Mesenchymal Stem Cell Treatment for Pneumonia Patients Infected With 2019 Novel Coronavirus	27-Jan-20	MSCs vs. control	Mild/Severe/ Critical	20	I	Recruiting	China