Novel coronavirus disease (COVID-19) is a respiratory illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease was named after the December 2019 coronavirus outbreak in Wuhan, China. The virus appears to have originated from bats.

Infected individuals may be asymptomatic or develop mild symptoms similar to those of seasonal influenza. More severe forms of the disease are characterized by acute viral pneumonia and shortness of breath, requiring urgent hospitalization. The infection may also affect the vascular and gastrointestinal systems as well as other organs.

The rapid development and deployment of COVID-19 vaccines have decreased infection rates in many countries. Several studies have shown that COVID-19 vaccination is effective at preventing severe disease and hospitalization.

The emergence of fast-spreading SARS-CoV-2 variants that can evade the immune system undermines public health efforts to control the spread of COVID-19. However, these variants are less virulent compared to the original parent strain, resulting in a lower disease burden among predominantly vaccinated populations. Nonetheless, individuals with preexisting conditions may experience more severe symptoms if infected with SARS-CoV-2, even if they are vaccinated. Therefore, susceptible individuals should take additional precautions. Wearing masks and practicing social distancing are highly effective measures for preventing infection and controlling the spread of COVID-19.