Abstract
BACKGROUND: The outbreak of the novel coronavirus (SARS-CoV-2) has led to a severe public health crisis worldwide, significantly impacting human lives and health. The clinical manifestations and severity of COVID-19 vary among individuals, influenced by factors such as lifestyle, underlying health conditions, and genetic predispositions. Among these factors, blood type has garnered considerable attention as a potential biological marker that may affect both the risk of SARS-CoV-2 infection and disease severity. METHODS: This retrospective study analyzed hospitalized COVID-19 patients at Fujian Medical University First Hospital from December 1, 2022, to January 31, 2023. Epidemiological information, clinical data, admission classification, ABO blood type, laboratory results, and clinical outcomes were extracted. Univariate analysis was used to compare clinical profiles and risk factors across blood types. RESULTS: A total of 823 patients (516 males, 307 females) were included. The results showed that Patients with mild/moderate disease at admission exhibited significantly higher cure rates, lower mortality, reduced pneumonia incidence, and younger age compared to severe/critical cases (P < 0.05). Furthermore, Forty-four laboratory indicators—including liver function, renal function, and coagulation parameters—showed significant intergroup differences. Notably, type B blood was associated with a reduced risk of progression to severe/critical disease (P < 0.05), though no significant correlation was observed between blood type and ultimate prognosis. CONCLUSION: Non-B blood types were associated with increased risks of severe/critical COVID-19 progression. Integrating ABO blood typing with clinical laboratory data may improve risk prediction for COVID-19 patients. These findings suggest that ABO blood type could serve as a predictive biomarker for SARS-CoV-2 infection severity. However, further mechanistic studies are required to elucidate the relationship between blood type and disease pathogenesis. CLINICAL TRIAL NUMBER: Not applicable. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12879-025-12439-4.