Association Between Acute COVID‐19 Infection and Long COVID in a Non‐Hospitalized Population: A Retrospective Case‐Control Study

Background and Aims Long COVID (LC) is a condition characterized by the persistence of physical or psychological symptoms after acute SARS‐CoV‐2 infection. While its pathophysiology remains unclear, it is essential to identify acute‐phase risk factors associated with its development. This study aimed to investigate the association between symptoms during acute COVID‐19 and the risk of developing LC, and to evaluate the impact of LC on functional status in a nonhospitalized population. Methods A retrospective observational case‐control study was conducted between May 2022 and March 2024 including 434 participants with confirmed SARS‐CoV‐2 infection. Participants were classified as cases (those with LC; n = 226) or controls (those without LC; n = 208). Data were collected using a structured electronic form, including self‐reported sociodemographic, clinical, and lifestyle information. Severity and number of acute symptoms were recorded. Functional status was assessed using the Post‐COVID functional status (PCFS) Scale. Logistic and linear regression analyses were performed to explore associations, adjusted for potential confounders. Results Severe acute COVID‐19 (defined as pneumonia or hospitalization) was associated with a significantly increased risk of LC (adjusted OR = 7.22; 95% CI: 2.79–18.70). Additionally, each additional symptom during the acute phase increased the odds of LC by 52% (adjusted OR = 1.52; 95% CI: 1.35–1.77). Dyspnea and chest pain were the symptoms most strongly associated with LC. Conclusion The severity and symptom burden of acute COVID‐19 are strongly associated with the development of LC and with long‐term functional impairment. These findings highlight the importance of early identification and follow‐up in patients with severe initial COVID‐19 symptoms.