CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
OPERATING ACTIVITIES
Net loss	$ (874)	$ (1,996)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	130	588
Depreciation	43	48
Change in fair value of warrant liability	(3)	100
Changes in operating assets and liabilities:
Grant receivable	55	0
Prepaid expenses and other current assets	136	98
Accounts payable	50	(14)
Accrued and other current liabilities	(97)	82
Net cash used in operating activities	(560)	(1,094)
INVESTING ACTIVITIES
Net cash used in investing activities	0	0
FINANCING ACTIVITIES
Proceeds from issuance of common stock and warrants	0	559
Proceeds from exercise of warrants	0	428
Net cash provided by financing activities	0	987
Net decrease in cash and restricted cash	(560)	(107)
Cash and restricted cash at beginning of period		963
Cash and restricted cash at end of period	$ 516	$ 856