Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 24, 2021	Jun. 30, 2020
Document Information [Line Items]
Entity Registrant Name	Vaxart, Inc.
Entity Central Index Key	0000072444
Trading Symbol	vxrt
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding (in shares)		117,766,672
Entity Public Float			$ 842,046,746
Entity Shell Company	false
Document Type	10-K
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Title of 12(b) Security	Common stock, $0.0001 par value