Clinical Presentations and Outcomes of Patients With Covid-19 Pneumonia

According to the World Health Organization (WHO), the emergence of viral diseases represents a serious public health risk. In the past two decades, several epidemics caused by viruses such as the severe acute respiratory syndrome coronavirus (SARS-CoV) from 2002 to 2003, and H1N1 influenza in 2009, and the Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 have been described which have had a significant impact on global health. Since being declared a global pandemic by the WHO, SARS-CoV-2, the virus responsible for COVID-19 has spread to 223 countries with more than 178 million confirmed cases, and more than 3.8 million deaths reported worldwide. The U.S. experienced the highest number of SARS-CoV-2 infections and COVID-19 related deaths followed by Brazil and India.

In fact, COVID-19 was the third leading cause of death in the U.S. in 2020 after heart disease and cancer, with approximately 375,000 death reported . As of 22 June 2021, the Alpha(B.1.1.7) variant has spread to 170 countries, the Beta (B.1.351) variant has been reported in 119 countries, the Gamma (P.1) variant has been detected in 71 countries and the Delta variant(B.1.617.2) has spread to 85 countries around the world based on the weekly epidemiological update by the WHO . The WHO's current estimate of the global case fatality rate for COVID-19 is 2.2%. However, the case fatality rate is affected by factors that include age, underlying preexisting conditions, and severity of illness and significantly varies between countries.

The common clinical features of COVID-19 pneumonia in adults include fever, dry cough, sore throat, headache, fatigue, myalgia and breathlessness . The disease manifestations in the infected patients range from mild pneumonia (81%) to moderate pneumonia (hypoxia requiring hospitalization, 14%), and critical illness (leading to invasive mechanical ventilation, multiorgan dysfunction and possibly death, 5%). The risk of death depends on age, underlying comorbidities and severity of the disease, increasing up to 49% in critically ill patients.