Visibility of the Korean National Health Information Portal across search engines and generative artificial intelligence platforms: a repeated cross-sectional study.

OBJECTIVES: This study assessed changes in the visibility of the National Health Information Portal (NHIP), operated by the Korea Disease Control and Prevention Agency, across conventional search portals and generative artificial intelligence (AI) platforms. METHODS: We analyzed 150 health-related keywords derived from NHIP traffic data, Daum search logs, and chronic disease categories across 7 platforms: Naver, Google, Bing, Daum, ChatGPT, Perplexity, and Gemini. Searches were conducted in September 2025 and February 2026; Gemini was assessed only in the second survey. NHIP exposure was defined as appearance within the top 10 organic search results, whereas AI citation was defined as explicit source attribution. Changes were tested using McNemar's test. RESULTS: Organic search exposure for the NHIP increased on Naver (64.0% to 73.3%, p=0.018) and decreased on Bing (72.0% to 61.3%, p=0.021). AI-summary citation rates increased more substantially on Naver AI Briefing (8.0% to 62.7%, p<0.001), Bing AI Summary (6.7% to 44.7%, p<0.001), Google AI Overview (30.0% to 48.0%, p=0.001), and ChatGPT (16.7% to 38.0%, p<0.001). Gemini cited the NHIP for 96.0% of keywords. For dyslipidemia-related keywords (n=10), Google and ChatGPT showed no NHIP exposure, whereas Gemini cited the NHIP for all keywords. CONCLUSION: AI citation represents a new dimension of health information accessibility. To address visibility gaps and marked platform divergence, public health portals should implement a 3-level optimization strategy encompassing machine-readable infrastructure, AI-friendly content formatting, and continuous multi-platform monitoring.