Subsequent Events - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jan. 19, 2022	Mar. 11, 2021	Nov. 13, 2020	Dec. 11, 2018	Jul. 31, 2018
Subsequent Event [Line Items]
Proceeds from sale of common stock to related party	$ 7,831,000	$ 13,166,000
BARDA [Member]
Subsequent Event [Line Items]
Potential amount additional funding awarded			$ 12,900,000
Overall potential award increased			46,900,000
Potential contract amount awarded			59,700,000				$ 44,200,000
At-The-Market Offering Program [Member]
Subsequent Event [Line Items]
Proceeds from sale of common stock to related party	8,100
At-The-Market Offering Program [Member] | Cantor Fitzgerald & Co [Member]
Subsequent Event [Line Items]
Common stock available for issuance	$ 344,205
Price per share	$ 10.86
Proceeds from sale of common stock to related party	$ 3,700,000
Sales Agreement [Member] | At-The-Market Offering Program [Member]
Subsequent Event [Line Items]
Common stock available for issuance					$ 34,000,000.0
Sales Agreement [Member] | At-The-Market Offering Program [Member] | Cantor Fitzgerald & Co [Member] | Maximum [Member]
Subsequent Event [Line Items]
Common stock available for issuance				$ 75,000,000.0		$ 50,000,000.0
Subsequent Event [Member] | BARDA [Member]
Subsequent Event [Line Items]
Potential amount additional funding awarded			12,900,000
Potential contract amount awarded			59,700,000
Subsequent Event [Member] | Maximum [Member] | BARDA [Member]
Subsequent Event [Line Items]
Overall potential award increased			$ 46,900,000