GSK starts a Phase III efficacy trial of FLUm3HA.b-3NA in September 2026.
GSK announced plans to advance the vaccine candidate to Phase III in September 2026. The milestone is met if the trial officially begins or doses its first patient before October 1, 2026.
Across 6 frontier models answering independently, the panel leans no: the median is 44%.
They do not agree: Qwen puts it at 78% and DeepSeek at 22%, 56 points apart. A spread that wide usually means the question turns on something none of them can see yet.
It happened. Every model on the panel is now scored against that, and the market is scored on the same question.
It happened.
GSK announced on Sept 1, 2026 its intention to start a Phase III efficacy trial of the mRNA flu vaccine candidate FLUm3HA.b-3NA in September 2026, and subsequent reporting (including a Reuters piece around GSK's Q3 results on Oct 28, 2026, and the GSK study register listing a study start date of September 2026) indicates the trial did start that month.
Three models agreed on the evidence A search-grounded model gathered the sources below; three models from three different labs then ruled on that evidence independently and reached the same answer.
- Claudehappeneddirect evidence
- GPThappeneddirect evidence
- Geminihappeneddirect evidence
- GSK to advance mRNA seasonal flu vaccine candidate to phase III following positive phase II data
- GSKTrial ID 218130 - GSK study register
- GSK mRNA flu shot to enter phase III in 2026 - Stock Titan
- GSK Advances mRNA Flu Vaccine to Phase III | PharmExec
- Stock-exchange announcement
- Your Questions Answered: The Biggest Pharma and Biotech Stories ...
What each one said
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QwenAlibaba
GSK announced intent; Phase III starts are often delayed by site/regulatory issues, but 2-week window is tight.
qwen/qwen3.8-max-0902 · asked 14 Sept 202678% -
GPTOpenAI
Company timing guidance is specific and near-term, but trial activation and first dosing often slip weeks.
openai/gpt-5.6-terra · asked 14 Sept 202663% -
ClaudeAnthropic
Company-stated timeline, but Phase III starts often slip past announced month by weeks
anthropic/claude-sonnet-5 · asked 14 Sept 202645% -
GeminiGoogle
Strict seasonal flu timing helps, but clinical trial starts routinely slip by several weeks into Q4.
google/gemini-3.8-flash · asked 14 Sept 202642% -
GrokxAI
Pharma Phase III starts routinely slip past announced months; 16 days left with no start signal.
x-ai/grok-4.6 · asked 14 Sept 202638% -
DeepSeekDeepSeek
Announced start dates slip; 17 days left, no registration or site news visible yet.
deepseek/deepseek-v4.1-flash · asked 14 Sept 202622%
6 of 6 models answered · 56 points between the highest and lowest. None was shown the market price.
Question sourced from a news sweep on 14 Sept 2026. Forecast by google/gemini-3.8-flash, anthropic/claude-sonnet-5, openai/gpt-5.6-terra, x-ai/grok-4.6, deepseek/deepseek-v4.1-flash, qwen/qwen3.8-max-0902 via OpenRouter.