Korean J Intern Med.  2021 Jan;36(1):1-10. 10.3904/kjim.2020.329.

Clinical implication and risk factor of pneumonia development in mild coronavirus disease 2019 patients

  • 1Division of Respiratory and Critical Care, Department of Internal Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, Korea


Although a majority of coronavirus disease 2019 (COVID-19) cases were characterized as mild, data assessing the development of pneumonia in mild COVID-19 patients are limited. We aimed to examine the effect of pneumonia development on the clinical course of mild COVID-19 in hospitalized patients.
A retrospective cohort study was conducted via medical record review between February 25, 2020 and April 11, 2020 at a single center. The impact of pneumonia development on the time to viral clearance in mild COVID-19 patients was evaluated. Risk factors associated with the development of pneumonia were also identified.
Chest radiographs revealed the development of pneumonia in 26.8% of mild COVID-19 patients. The time to pneumonia development was a median of 8.0 days from the onset of symptoms and 3.5 days after hospital admission. A multivariate analysis for predicting pneumonia development identified age ≥ 65 years (odds ratio [OR], 3.15; 95% confidence interval [CI], 1.14 to 8.73), cough (OR, 2.18; 95% CI, 1.29 to 3.68), dyspnea (OR, 3.58; 95% CI, 1.10 to 11.69), and diarrhea (OR, 2.69; 95% CI, 1.51 to 4.78) as significant variables. The time to negative conversion was longer in mild COVID-19 patients who developed pneumonia (23.6 days vs. 18.4 days, p = 0.003). In Kaplan–Meier estimation and multivariate Cox regression analyses, newly developed pneumonia was significantly related with delayed time to negative conversion (log-rank test, p = 0.02; hazard ratio, 2.90; 95% CI, 1.06 to 7.97).
The development of pneumonia delayed viral clearance in patients with mild COVID-19. Elderly patients or those suffering from diarrhea should be closely monitored, given the increased risk of developing pneumonia.


COVID-19; Pneumonia; Viruses; Mortality; Risk factors
Full Text Links
  • KJIM
export Copy
  • Twitter
  • Facebook
Similar articles
    DB Error: unknown error