| Segment Reporting [Table Text Block] |
| | | Three Months Ended June 30, | | | Six Months Ended June 30, | |
| | | 2026 | | | 2025 | | | 2026 | | | 2025 | |
| Revenue | | $ | 27,185 | | | $ | 39,730 | | | $ | 66,413 | | | $ | 60,606 | |
| Less: | | | | | | | | | | | | | | | | |
| Research and development | | | | | | | | | | | | | | | | |
| External program costs: | | | | | | | | | | | | | | | | |
| Norovirus program | | | 139 | | | | 1,152 | | | | 186 | | | | 2,708 | |
| COVID-19 program | | | 25,922 | | | | 36,475 | | | | 46,316 | | | | 52,193 | |
| Other programs | | | — | | | | 40 | | | | — | | | | 346 | |
| Preclinical research | | | 53 | | | | 225 | | | | 134 | | | | 624 | |
| Process Development | | | — | | | | — | | | | — | | | | 46 | |
| Internal research and development costs | | | 7,640 | | | | 11,843 | | | | 16,531 | | | | 24,562 | |
| General and administrative | | | 6,603 | | | | 4,598 | | | | 11,244 | | | | 9,665 | |
| Interest income | | | (578 | ) | | | (310 | ) | | | (1,129 | ) | | | (747 | ) |
| Non-cash interest expense related to sale of future royalties | | | 538 | | | | 672 | | | | 1,043 | | | | 1,669 | |
| Other segment items(A) | | | 333 | | | | 1 | | | | 345 | | | | 2 | |
| Provision for income taxes | | | 29 | | | | 20 | | | | 58 | | | | 115 | |
| Segment net loss | | $ | (13,494 | ) | | $ | (14,986 | ) | | $ | (8,315 | ) | | $ | (30,577 | ) |
| Reconciliation of net loss | | | | | | | | | | | | | | | | |
| Adjustments and reconciling items | | | — | | | | — | | | | — | | | | — | |
| Net loss | | $ | (13,494 | ) | | $ | (14,986 | ) | | $ | (8,315 | ) | | $ | (30,577 | ) |
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