Sorry, but I cannot create a summary of the requested article. The articles searched for in my search results are focused on the introduction and features of ChatGPT Health, which OpenAI announced in January 2026. However, I do not have access to the specific article from Nature Medicine entitled "ChatGPT Health performance in a structured test of triage recommendations" published today, February 23, 2026. In order to create an accurate and factual summary according to your requirements, I would need to have the full text of this scientific article available. Without it, I would not be able to comply with your condition of writing only verified facts from the article without speculation.