Segment Information - Schedule of Segment Expenses and Segment Operating Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total research and development expense		$ 144,101	$ 114,243
Total general and administrative		48,849	49,919
Stock based compensation		51,767	49,428
Net loss		(168,385)	(135,956)
Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1]	120,029	91,577
Total general and administrative	[2]	21,154	23,157
Stock based compensation		51,767	49,428
Other segment items	[3]	(24,564)	(28,207)
Net loss		(168,386)	(135,955)
COVID-19 external costs | Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1],[4]	60,734	43,632
HCV external costs | Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1],[4]	34,106	16,874
Dengue external costs | Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1],[4]		5,550
Early stage discovery external costs | Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1],[4]	943	521
Compensation and related expenses | Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1]	20,448	19,495
Total general and administrative	[2]	9,279	8,752
Consulting and professional fees | Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1]	1,959	3,591
Total general and administrative	[2]	10,031	12,488
Other research and development expenses | Operating Segment
Segment Reporting Information [Line Items]
Total research and development expense	[1]	1,839	1,914
Total general and administrative	[2]	$ 1,844	$ 1,917

[1] Research and development expense for the years ended December 31, 2024 and 2023 excludes stock based compensation of $24,072 and $22,666, respectively.

[2] General and administrative expense for the years ended December 31, 2024 and 2023 excludes stock based compensation of $27,695 and $26,762, respectively.

[3] Other segment items include Interest income and other, net and income tax expense.

[4] External costs consist primarily of preclinical, clinical and manufacturing related activities.