ChatGPT’s new GPT-5.5 Instant model brings significant health intelligence improvements, helping over 230 million users with health and wellness questions. The model’s advancements in recognizing urgent care needs, asking relevant context, and explaining uncertainty make complex health information easier to understand. Physician-led evaluations and health-specific assessments have driven these improvements, ensuring accurate and understandable responses. Why it matters: this progress has the potential to greatly impact public health by providing reliable and accessible health information to a massive user base.