Coronavirus, the disease that began in 2019, is a highly infectious disease caused by severe acute respiratory syndrome coronavirus 2. First discovered in December 2019 in Wuhan, China, the outbreak of this virus has resulted in an ongoing pandemic. The first case can be traced back to November 17, 2019. With more than 7 million cases have been confirmed worldwide, resulting in more than 400,000 deaths, with more than 1 million people who have recovered. Common symptoms include fever, cough, fatigue, shortness of breath, and loss of smell and taste. The time from exposure to onset of symptoms is typically around five days, but may range from two to fourteen days.
The virus is spread primarily between people during close contact, most often from small droplets produced by coughing, sneezing, and talking. The droplets usually fall to the ground or onto surfaces rather than travelling through air over long distances. Chest CT imaging may also be helpful for diagnosis in individuals who have a high suspicion of infection based on symptoms and risk factors; however, guidelines do not recommend using CT imaging for routine screening.
Recommended measures to prevent infection include very frequent hand washing, maintaining distance from others, quarantine, covering coughs, and keeping unwashed hands away from the face. The use of cloth face coverings such as a scarf or a bandana is recommended in public settings to minimise the risk of transmissions, with some authorities requiring their use. Medical grade face masks such as N95 masks should only be used by healthcare workers, first responders and those who care for infected individuals.
According to the World Health Organization, there are no vaccines or specific treatments for COVID-19. The World Health Organization declared the COVID‑19 outbreak a public health emergency of international concern on January 30 2020 and a pandemic on March 11 2020.
Fever is the most common symptom, but it is highly variable in severity and presentation, with some older or critically ill people not experiencing a fever at all. In one study, only 44% of people had a fever when they presented to the hospital, while 89% went on to develop a fever at some point during their hospitalization. A lack of fever does not verify someone is disease free. Other common symptoms include cough, loss of appetite, fatigue, shortness of breath, sputum production, and muscle and joint pains. Symptoms such as nausea, vomiting, and diarrhoea have been observed in varying percentages. Less common symptoms include sneezing, runny nose, sore throat, and skin lesions. Some cases in China initially presented with only chest tightness and palpitations. Less sense of smell or disturbances in taste may occur. Loss of smell was a presenting symptom in 30% of confirmed cases in South Korea.
As is common with infections, there is a delay between the moment a person is first infected and the time he or she develops symptoms. This is called the incubation period. The typical incubation period for COVID‑19 is five or six days, but it can range from one to fourteen days with approximately ten percent of cases taking longer. An early key to the diagnosis is the tempo of the illness. Early symptoms may include a wide variety of symptoms but infrequently involves shortness of breath. Shortness of breath usually develops several days after initial symptoms. The most critical days of illness tend to be those following the development of shortness of breath.
A minority of cases do not develop noticeable symptoms at any point in time. These asymptomatic carriers tend not to get tested, and their role in transmission is not yet fully known. However, preliminary evidence suggests they may contribute to the spread of the disease, which is why social distancing is so effective in curbing the spread of coronavirus worldwide.