The SARS-CoV-2 Outbreak: an Epidemiological and Clinical Perspective

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak started with the detection of an increasing number of pneumonia cases of unknown origin in Wuhan, China, since December 2019. The disease caused by SAS-CoV-2 was subsequently named coronavirus disease 2019 (COVID-19). Currently, the ongoing COVID-19 pandemic poses a global health concern with more than 28.9 million confirmed cases, taking away the lives of more than 900,000 people worldwide. To prevent further spread of the disease, an understanding of the clinical characteristics and how the disease spread is essential, especially for an emerging disease like COVID-19. Individuals who are infected with SARS-CoV-2 show diverse clinical features, and the disease severity can range from asymptomatic to death. The disease has been shown to affect not just the respiratory system but also other systems of the body. This review will discuss the pulmonary and extra-pulmonary clinical manifestations of COVID-19 in general, as well as the clinical characteristics in different groups of patients such as children, the elderly, pregnant women, patients with comorbidities and those with a compromised immunity. It will also critically examine existing evidence from relevant studies and discuss the SARS-CoV-2 outbreak from an epidemiological perspective. With the easing of control measures in many countries after months of lockdown, it is important to revisit the lessons learnt from research, as the world enters a new normal with the coexistence of SARS-CoV-2.