Rapid antigen swab: a promising tool in scaling up coronavirus disease 2019 detection in a variety of pulmonary and extrapulmonary manifestations?

Background Coronavirus disease 2019 (COVID-19) is a severe infectious disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Regarding the ongoing spread of COVID-19 in Egypt, this study aimed to determine the sensitivity and specificity of rapid COVID antigen swab in the diagnosis of COVID-19 infection in pulmonary and extrapulmonary manifestations of COVID-19 and discuss the pulmonary and extrapulmonary symptoms of COVID-19. Patients and methods This is a cross-sectional study performed on 447 patients diagnosed with COVID-19 at the chest out-patient clinic or Department of Chest and ICU in Menoufia University Hospital during the period from July 2021 to March 2022. Detailed history, full laboratory data, high-resolution computed tomography, and rapid antigen swab were obtained. Results A total of 447 patients were included in this study. They were classified into two groups: group 1 included 105 patients with pulmonary symptoms and group 2 included 342 patients with extrapulmonary symptoms in the absence or presence of pulmonary symptoms. The current study showed a sensitivity of 88.6% and specificity of 100% regarding the rapid antigen swab in diagnosing COVID-19. Regarding the extrapulmonary symptoms, muscle ache was the most common symptom in 52% of the patients followed by loss of taste and smell in 39.8% of patients. Conclusion Rapid antigen tests are practical, are reliable, provide fast results (~15 min), and are cheap diagnostic methods with high sensitivity and specificity for COVID-19. Moreover, it showed a wide range of extrapulmonary symptoms of COVID-19, and every symptom revealed should be suspected and investigated.