ASL-4 virology uplift trial (Anthropic)
PhD experts with model access write a protocol to reconstruct a challenging virus. Graded by a rubric with critical failures.
Human uplift trial designed by Deloitte. Uplift is the ratio to an internet-only control group.
- Level
- Expert Specialists with years of training, often over hours of work
- Scored
- Graded by people Human experts grade or compare the outputs.
- Answers
- Open-ended Free-form text, documents, designs or media judged as a whole.
Claude Opus 4.5 leads with 66.8% among models released by Apr 2026
Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.
The newest model with a score here came out in Apr 2026, and nobody has reported a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:
- GPT-6 Astra
- Claude Opus 5.5
- GPT-6.1 Terra
- GPT-6.1 Sol
- and 16 more
- 1 Claude Opus 4.5 66.8%
- 2 Claude Mythos Preview 64%
- 3 Claude Opus 4.6 52%
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | Claude Opus 4.5 | 66.8% | Nov 2025 | Model card | |
| 2 | Claude Mythos Preview | 64% | Apr 2026 | Model card | |
| 3 | Claude Opus 4.6 | 52% | Feb 2026 | Model card |
Number one over time
Lab claims count from the day the card came out, independent runs from the model’s release.
Scores over time
All the scores we have, one dot each, so a model tested at several settings appears more than once.
Labs report it only in system cards
We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark. Some system cards do, below.
3 system cards report it, from 1 lab
Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.
| Date | Document | Score | As the document writes it | Section |
|---|---|---|---|---|
| 7 Apr 2026 | Claude Mythos Preview system card | 64 | Virology protocol uplift trial, mean fractional protocol score of Mythos Preview-assisted participants 0.64 ± 0.09 (n=12), value printed on chart; 4.3 ± 1.2 mean critical failures of 18, agentic runs 0.68 and 4.0 (2.2.5.2, Figure 2.2.5.2.A) | Bio and chem risk |
| 5 Feb 2026 | Claude Opus 4.6 system card | 52 | ASL-4 virology protocol uplift trial, average protocol score of model-assisted participants 0.52, 6.6 mean critical failures of 18, 3-day trial (8.2.4.5) | Bio and chem risk |
| 24 Nov 2025 | Claude Opus 4.5 system card | 66.8 | ASL-4 virology uplift trial, mean protocol score of model-assisted participants 0.668 (7.2.4.8; 1.97x uplift over internet-only control, 5.8 mean critical failures of 18) | Bio and chem risk |
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