A Narrative Review of COVID-19: The New Pandemic Disease

Abstract

Nearly every 100 years, humans collectively face a pandemic crisis. After the Spanish flu, now the world is in the grip of coronavirus disease 2019 (COVID-19). First detected in 2019 in the Chinese city of Wuhan, COVID-19 causes severe acute respiratory distress syndrome. Despite the initial evidence indicating a zoonotic origin, the contagion is now known to primarily spread from person to person through respiratory droplets. The precautionary measures recommended by the scientific community to halt the fast transmission of the disease failed to prevent this contagious disease from becoming a pandemic for a whole host of reasons. After an incubation period of about two days to two weeks, a spectrum of clinical manifestations can be seen in individuals afflicted by COVID-19: from an asymptomatic condition that can spread the virus in the environment, to a mild/moderate disease with cold/flu-like symptoms, to deteriorated conditions that need hospitalization and intensive care unit management, and then a fatal respiratory distress syndrome that becomes refractory to oxygenation. Several diagnostic modalities have been advocated and evaluated; however, in some cases, diagnosis is made on the clinical picture in order not to lose time. A consensus on what constitutes special treatment for COVID-19 has yet to emerge. Alongside conservative and supportive care, some potential drugs have been recommended and a considerable number of investigations are ongoing in this regard.

Keywords: SARS virus; COVID-19; Coronavirus; Epidemiology; Pandemics.

Figure 1

Most cases with SARS-CoV-2 are asymptomatic or have mild clinical pictures such as influenza and colds. This group of patients should be detected and isolated in their homes to break the transmission chain of the disease and adhere to the precautionary recommendations in order not to infect other people. The screening process will help this group and suppress the outbreak in the community. Patients with the confirmed disease who are admitted to hospitals can contaminate this environment, which should be borne in mind by healthcare providers and policymakers.

Figure 2

SARS-CoV-2 mode of transmission and clinical manifestations are illustrated in this figure. The potential source of this outbreak was identified to be from animals, similar to MERS and SARS, in epidemiologic studies; nonetheless, person-to-person transmission through droplets is currently the important mode. After reaching mucous membranes by direct or indirect close contact, the virus replicates in the cells and the immune system attacks the body due to its nature. Afterward, the clinical pictures appear, which are much more similar to influenza. However, different patients will have a spectrum of signs and symptoms.