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Note 15 - Subsequent Events (Details Textual) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	2 Months Ended
	Jan. 31, 2024	Mar. 14, 2024	Feb. 27, 2024	Jan. 12, 2024	Nov. 30, 2022
Grant [Member]
Grants Receivable					$ 3.5
Subsequent Event [Member] \| The 2024 Inducement Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)			3,000,000
Subsequent Event [Member] \| Grant [Member] \| Department of Health and Human Services, ASPR [Member]
Grants Receivable				$ 9.3
Subsequent Event [Member] \| RA Capital Healthcare Fund 2024 [Member]
Stock Issued During Period, Shares, New Issues (in shares)	15,384,615
Shares Issued, Price Per Share (in dollars per share)	$ 0.65
Gross Proceeds from Issuance of Common Stock	$ 10.0
Net Proceeds From Issuance of Common Stock	$ 9.9
Subsequent Event [Member] \| ATM Program [Member]
Stock Issued During Period, Shares, New Issues (in shares)		5,071,472
Net Proceeds From Issuance of Common Stock		$ 5.7