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Article History

Received: 28 November 2025

Accepted: 14 May 2026

First Online: 25 May 2026

Declarations

:

: The authors declare no competing interests.

: This study was approved by the Ethics Review Committee of the Xining Center for Disease Control and Prevention (Approval No. qhxncdcllsc—2025020) and followed relevant guidelines. Patient data, summarized at the city level, were retrospective and involved low-risk studies. All personal information involved in this article was conducted under the supervision of the relevant researchers at the Xining Municipal Center for Disease Control and Prevention, and only secondary aggregated data were used in the analysis, which did not involve participants’ names, identifying information, telephone numbers, or residential addresses; therefore, the Ethics Review Committee of the Xining Center for Disease Control and Prevention waived written informed consent.