Thanit Sila: Department of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Wisanuwee Suriyaamorn: Division of Digital Innovation and Data Analytics, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Chanavee Toh: Department of Health Science and Clinical Research, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Songyos Rajborirug: Department of Epidemiology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Smonrapat Surasombatpattana: Department of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Paramee Thongsuksai: Department of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Chanon Kongkamol: Division of Digital Innovation and Data Analytics, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Sarunyou Chusri: Department of Internal Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
Phoomjai Sornsenee: Faculty of Medicine, Department of Family Medicine and Preventive Medicine, Prince of Songkla University, Hat Yai, Songkla, Thailand.
Prasit Wuthisuthimethawee: Department of Emergency Medicine, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
Raya Chaowanawong: Faculty of Nursing, Prince of Songkla University, Hat Yai, Songkla, Thailand.
Surasak Sangkhathat: Department of Biomedical Sciences and Biomedical Engineering, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Thammasin Ingviya: Division of Digital Innovation and Data Analytics, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.
Introduction: This study aimed to investigate factors associated with time-to-referral due to worsening symptoms in patients with laboratory-confirmed COVID-19 in southern Thailand. While underlying diseases have been evaluated to assess COVID-19 severity, the influence of vaccinations and treatments is also crucial. Methods: A cohort of 8,638 patients quarantined in home or community isolation with laboratory-confirmed COVID-19 was analyzed. Survival analysis and the Cox proportional hazard ratio were employed to assess factors influencing time-toreferral. Results: Age ��� 60 years, neurologic disorders, cardiovascular disease, and human immunodeficiency virus infection were identified as significant risk factors for severe COVID-19 referral. patients who received full- or booster-dose vaccinations had a lower risk of experiencing severe symptoms compared to unvaccinated patients. Notably, individuals vaccinated during the Omicron-dominant period had a substantially lower time-to-referral than those unvaccinated during the Delta-dominant period. Moreover, patients vaccinated between 1 and 6 months prior to infection had a significantly lower risk of time-to-referral than the reference group. Discussion: These findings demonstrate early intervention in high-risk COVID-19patients and the importance of vaccination efficacy to reduce symptom severity. The study provides valuable insights for guiding future epidemic management strategies and optimising patient care during infectious disease outbreaks.
