Coronavirus disease 2019
Coronavirus disease 2019 (English: Coronavirus disease 2019 , abbreviation: COVID-19   ), is an infectious disease caused by severe acute respiratory syndrome coronavirus type 2 (abbreviation: SARS-CoV-2) . The first known patient of the disease was diagnosed at the end of 2019 in Wuhan City, Hubei Province, People’s Republic of China  [Note 1] . Since then, the disease broke out on a large scale and spread rapidly in various countries around the world , becoming the most fatal epidemic in human history One of the diseases . As of February 17, 2021, more than 109 million confirmed cases have been reported in 192 countries and regions around the world, and more than 2.421 million patients have died  . The spread is still ongoing. The estimated value of the fatality rate of this disease varies greatly among countries in the world . As of February 8, 2021, the observed fatality rate of this disease in most countries is between 0.5% and 5.0%  [Note 2] , the global preliminary revised fatality rate About 2.9%  .
Common symptoms of the disease include fever , cough , fatigue , shortness of breath , and loss of taste and smell     . Although most people have mild symptoms, some people may develop acute respiratory distress syndrome (ARDS) due to cytokine storm  , multiple organ failure , septic shock, and thrombosis    . The time from infection to onset of symptoms is usually about 5 days, but it may be between 2 and 14 days   .
The virus is spread mainly through oral and nasal secretions, including respiratory droplets from coughing [Note 3] , sneezing, and talking    . These droplets usually do not travel long distances in the air   . However, people standing close may be infected by inhaling these droplets [Note 4] . People can also become infected by touching a contaminated surface and then touching their own face   . In the closed space may also be capable of being suspended by a long time in air aerosol dissemination  . It is most contagious in the first three days after the onset of symptoms, although it may spread before the onset of symptoms and in asymptomatic people   , and studies have shown that about 40%-45% of patients are asymptomatic Infected   . Diagnostic standard methods via the nasal swabs of reverse transcription polymerase chain reaction for diagnosis (the PCR-rRT)  . Chest CT imaging can also help diagnose individuals who are highly suspected of infection based on symptoms and risk factors  .
Suggested measures to prevent infection include frequent hand washing , social distancing with others , isolation and quarantine , covering your nose and mouth when coughing, and avoiding touching your eyes, nose, and mouth    . Wearing masks in public places can be very effective in reducing the risk of transmission   . The World Health Organization (WHO) declared the outbreak of COVID-19 as a public health emergency (PHEIC) of international concern on January 30, 2020,  and assessed on March 11, 2020 that COVID-19 has been It has pandemic characteristics  . Local transmission of the disease has occurred in most countries in all six regional offices of the World Health Organization  . United Nations Secretary-General Guterres believes that the COVID – 19 epidemic is the most severe crisis facing humanity since World War II