Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Grant revenue	$ 191	$ 883	$ 937	$ 1,631
Operating expenses:
Research and development	8,761	5,192	15,740	9,105
General and administrative	3,225	3,381	6,904	6,174
Total operating expenses	11,986	8,573	22,644	15,279
Loss from operations	(11,795)	(7,690)	(21,707)	(13,648)
Interest income	54	8	62	18
Net loss	$ (11,741)	$ (7,682)	$ (21,645)	$ (13,630)
Net loss per share, basic	$ (0.23)	$ (0.16)	$ (0.44)	$ (0.28)
Net loss per share, diluted	$ (0.23)	$ (0.16)	$ (0.44)	$ (0.28)
Weighted-average shares outstanding, basic	50,064	49,364	49,748	49,230
Weighted-average shares outstanding, diluted	50,064	49,364	49,748	49,230