Hospital Readmissions in Patients with Severe Acute Respiratory Syndrome: A Retrospective Study in Northeastern Brazil

Background/Objectives: Severe acute respiratory syndrome (SARS) remains an important cause of hospitalization and mortality, particularly among vulnerable populations. Understanding the factors associated with previous hospitalization may support more effective prevention and vaccination strategies. This study aimed to analyze the epidemiological profile of previous hospitalization among patients with SARS in the state of Pernambuco, Brazil. Methods: A quantitative, retrospective, cross-sectional study was conducted using data from the Influenza Epidemiological Surveillance System (SIVEP-Gripe), including 79,852 adult patients (≥18 years) notified with SARS in Pernambuco between 2021 and 2024. Sociodemographic, clinical, and vaccination-related variables were analyzed to identify factors associated with previous hospitalization. Results: The prevalence of previous hospital admission (readmission history) was 6.6%. Patients with previous hospitalization had a significantly higher median age compared to those without previous hospitalization (66 vs. 63 years; p < 0.001). The prevalence of previous hospitalization was higher among individuals with chronic comorbidities, particularly hematologic diseases (prevalence ratio [PR] = 1.95; 95% confidence interval [CI]: 1.51–2.51; p < 0.001) and asthma (PR = 1.67; 95% CI: 1.42–1.96; p < 0.001). Influenza vaccination was associated with a lower prevalence of previous SARS hospitalization (PR = 1.29; 95% CI: 1.03–1.61; p = 0.023). In contrast, COVID-19 vaccination status showed no significant association with previous hospitalization. A history of previous SARS hospitalization was associated with a higher prevalence of death in subsequent hospitalizations (PR = 1.09; 95% CI: 1.01–1.18; p = 0.022). Conclusions: Older adults and individuals with chronic comorbidities showed a higher prevalence of previous SARS hospitalization in Pernambuco. The findings show an association between influenza vaccination and a lower prevalence of previous SARS hospitalization and highlight the importance of post-discharge follow-up and epidemiological surveillance.