Citation, DOI & article data
This summary article is intended to be used as a quick reference guide. Please see our complete COVID-19 article for more detail.
COVID-19 (coronavirus disease 2019) is a viral infectious disease caused by SARS-CoV-2 and is currently a World Health Organizatiοn (WHO) declared pandemic. As of November 2021, over 245 million people had been infected globally with over 5 million deaths 13.
Many people with SARS-CoV-2 infection are asymptomatic 9. Symptoms and signs of COVID-19 are non-specific 1 but in symptomatic individuals most commonly include:
- fever (85-90%)
- cough (65-70%) with sputum (30-35%)
- smell and taste disturbances (50%) 12
- fatigue (35-40%)
- shortness of breath (15-20%)
The likelihood of severe illness requiring hospitalization correlates closely with male sex, advanced age and presence of comorbidities.
- ~5% admitted patients require ICU admission
Multiple serious sequelae have been reported including:
- acute respiratory distress syndrome (ARDS)
- coagulopathy: including PE and DIC
- secondary infections, e.g. bacterial pneumonia
- myocardial injury
- acute kidney injury (AKI)
- multiorgan failure
- secondary hemophagocytic lymphohistiocytosis
SARS-CoV-2 is a member of the Betacoronavirus genus, one of the genera of the Coronaviridae family of viruses. SARS-CoV-2 is indirectly zoonotic, but transmission is now primarily interhuman. The closest animal coronavirus by genetic sequence is a bat coronavirus 5. The cause of death is usually respiratory failure secondary to massive alveolar injury.
The primary findings of COVID-19 are those of an atypical or organizing pneumonia 2,3. Up to 18% of cases demonstrate normal chest x-rays or CT when mild/early in the disease course 10. Bilateral and/or multilobar involvement is common, more often with a lower zone distribution.
- patchy or diffuse airspace opacities, whether consolidation or ground-glass opacity 10,11
- pleural effusion is rare 11
The primary findings on CT chest in adults are 2,3,16:
- ground-glass opacities (GGO)
- crazy paving appearance (GGOs with septal thickening)
- air space consolidation
- bronchovascular thickening in the lesion
- traction bronchiectasis
- subpleural sparing
Treatment and prognosis
There are several therapeutic approaches: some of them inhibit the replication of the virus, others reduce the inflammatory response (e.g. interleukin inhibitors), whilst others inhibit coagulation 17,18,22.
Treatment is primarily supportive including mechanical ventilation for some patients. Dexamethasone has been shown to reduce mortality in ventilated patients or those on oxygen therapy 14.
Several highly-effective vaccines have now received regulatory approval in multiple territories: some of them use mRNA technology; others the technology of the adenoviral vector 15,20,21.
The mortality rate is estimated to be 3.6% 10.
The persistence of disabling symptoms long after the acute illness has resolved has become known as long COVID 19.
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- 2. Huang C, Wang Y, Li X et al. Clinical Features of Patients Infected with 2019 Novel Coronavirus in Wuhan, China. The Lancet. 2020;395(10223):497-506. doi:10.1016/s0140-6736(20)30183-5
- 3. Kanne J, Little B, Chung J, Elicker B, Ketai L. Essentials for Radiologists on COVID-19: An Update—Radiology Scientific Expert Panel. Radiology. 2020;296(2):E113-4. doi:10.1148/radiol.2020200527 - Pubmed
- 4. Zhao W, Zhong Z, Xie X, Yu Q, Liu J. Relation Between Chest CT Findings and Clinical Conditions of Coronavirus Disease (COVID-19) Pneumonia: A Multicenter Study. AJR Am J Roentgenol. 2020;214(5):1072-7. doi:10.2214/ajr.20.22976
- 5. Ng L & Hiscox J. Coronaviruses in Animals and Humans. BMJ. 2020;368:m634. doi:10.1136/bmj.m634 - Pubmed
- 6. Guo Y, Cao Q, Hong Z et al. The Origin, Transmission and Clinical Therapies on Coronavirus Disease 2019 (COVID-19) Outbreak – an Update on the Status. Military Med Res. 2020;7(1):11. doi:10.1186/s40779-020-00240-0 - Pubmed
- 7. Dai W, Zhang H, Yu J et al. CT Imaging and Differential Diagnosis of COVID-19. Can Assoc Radiol J. 2020;71(2):195-200. doi:10.1177/0846537120913033 - Pubmed
- 8. Li Y & Xia L. Coronavirus Disease 2019 (COVID-19): Role of Chest CT in Diagnosis and Management. AJR Am J Roentgenol. 2020;214(6):1280-6. doi:10.2214/ajr.20.22954
- 9. Mizumoto K, Kagaya K, Zarebski A, Chowell G. Estimating the Asymptomatic Proportion of Coronavirus Disease 2019 (COVID-19) Cases on Board the Diamond Princess Cruise Ship, Yokohama, Japan, 2020. Eurosurveillance. 2020;25(10):2000180. doi:10.2807/1560-7917.es.2020.25.10.2000180
- 10. Rodrigues J, Hare S, Edey A et al. An Update on COVID-19 for the Radiologist - A British Society of Thoracic Imaging Statement. Clinical Radiology. 2020;75(5):323-5. doi:10.1016/j.crad.2020.03.003 - Pubmed
- 11. Wong H, Lam H, Fong A et al. Frequency and Distribution of Chest Radiographic Findings in Patients Positive for COVID-19. Radiology. 2020;296(2):E72-8. doi:10.1148/radiol.2020201160 - Pubmed
- 12. Tong J, Wong A, Zhu D, Fastenberg J, Tham T. The Prevalence of Olfactory and Gustatory Dysfunction in COVID-19 Patients: A Systematic Review and Meta-Analysis. Otolaryngol Head Neck Surg. 2020;163(1):3-11. doi:10.1177/0194599820926473 - Pubmed
- 13. Wuhan Coronavirus (2019-nCoV) Global Cases (by Johns Hopkins CSSE). Case Dashboard. [accessed 1 November 2021].
- 14. The RECOVERY Collaborative Group. Dexamethasone in Hospitalized Patients with Covid-19. N Engl J Med. 2021;384(8):693-704. doi:10.1056/nejmoa2021436
- 15. Ledford H. US Authorization of First COVID Vaccine Marks New Phase in Safety Monitoring. Nature. 2020;588(7838):377-8. doi:10.1038/d41586-020-03542-4 - Pubmed
- 16. Prokop M, van Everdingen W, van Rees Vellinga T et al. CO-RADS: A Categorical CT Assessment Scheme for Patients Suspected of Having COVID-19—Definition and Evaluation. Radiology. 2020;296(2):E97-E104. doi:10.1148/radiol.2020201473 - Pubmed
- 17. Iyer M, Jayaramayya K, Subramaniam M et al. COVID-19: An Update on Diagnostic and Therapeutic Approaches. BMB Rep. 2020;53(4):191-205. doi:10.5483/bmbrep.2020.53.4.080
- 18. Zhou G, Chen S, Chen Z. Advances in COVID-19: The Virus, the Pathogenesis, and Evidence-Based Control and Therapeutic Strategies. Front Med. 2020;14(2):117-25. doi:10.1007/s11684-020-0773-x - Pubmed
- 19. Ramakrishnan R, Kashour T, Hamid Q, Halwani R, Tleyjeh I. Unraveling the Mystery Surrounding Post-Acute Sequelae of COVID-19. Front Immunol. 2021;12:686029. doi:10.3389/fimmu.2021.686029 - Pubmed
- 20. Heinz F & Stiasny K. Distinguishing Features of Current COVID-19 Vaccines: Knowns and Unknowns of Antigen Presentation and Modes of Action. Npj Vaccines. 2021;6(1):104. doi:10.1038/s41541-021-00369-6 - Pubmed
- 21. Walter E, Talaat K, Sabharwal C et al. Evaluation of the BNT162b2 Covid-19 Vaccine in Children 5 to 11 Years of Age. N Engl J Med. 2021. doi:10.1056/nejmoa2116298
- 22. Cavalli G, Larcher A, Tomelleri A et al. Interleukin-1 and Interleukin-6 Inhibition Compared with Standard Management in Patients with COVID-19 and Hyperinflammation: A Cohort Study. The Lancet Rheumatology. 2021;3(4):e253-61. doi:10.1016/s2665-9913(21)00012-6