Subsequent Event	9 Months Ended
Sep. 30, 2026
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On October 9, 2026, the Company and Gilead Sciences, Inc. (Gilead) entered into a Collaboration and License Agreement (the Gilead Collaboration Agreement). Under the terms of the Gilead Collaboration Agreement, the Company will be responsible for discovery, design and optimization of three novel PRO-XTEN® dual-masked TCE preclinical development candidates targeting selected solid tumor-associated antigens. Gilead will have an exclusive license to nominate and advance candidates generated under the collaboration and will be responsible for subsequent development, manufacturing and commercialization activities. Concurrently with the execution of the Gilead Collaboration Agreement, the Company and Gilead also entered into a Stock Purchase Agreement (the Gilead SPA), pursuant to which Gilead purchased 1,765,486 shares of Vir Bio’s common stock at $14.16 per share for an aggregate purchase price of approximately $25.0 million. The Gilead SPA includes standstill, voting and lockup provisions, with customary exceptions, that expire one year after the date of the closing of the Gilead SPA. The Company received $90.0 million cash consideration in October 2026, which included $65.0 million in upfront payment and the $25.0 million equity investment. The Company will be eligible to receive up to $45.0 million in potential near-term preclinical milestones and up to $1.74 billion in further development, regulatory and commercial milestones, along with tiered high single-digit to low double-digit royalties on net sales.

On October 9, 2026, the Company and Gilead Sciences, Inc. (Gilead) entered into a Collaboration and License Agreement (the Gilead Collaboration Agreement). Under the terms of the Gilead Collaboration Agreement, the Company will be responsible for discovery, design and optimization of three novel PRO-XTEN® dual-masked TCE preclinical development candidates targeting selected solid tumor-associated antigens. Gilead will have an exclusive license to nominate and advance candidates generated under the collaboration and will be responsible for subsequent development, manufacturing and commercialization activities.

Concurrently with the execution of the Gilead Collaboration Agreement, the Company and Gilead also entered into a Stock Purchase Agreement (the Gilead SPA), pursuant to which Gilead purchased 1,765,486 shares of Vir Bio’s common stock at $14.16 per share for an aggregate purchase price of approximately $25.0 million. The Gilead SPA includes standstill, voting and lockup provisions, with customary exceptions, that expire one year after the date of the closing of the Gilead SPA.

The Company received $90.0 million cash consideration in October 2026, which included $65.0 million in upfront payment and the $25.0 million equity investment. The Company will be eligible to receive up to $45.0 million in potential near-term preclinical milestones and up to $1.74 billion in further development, regulatory and commercial milestones, along with tiered high single-digit to low double-digit royalties on net sales.