Some people with the coronavirus do not have symptoms at all. Diagnosis by examination alone is difficult since many COVID-19 signs and symptoms can be caused by other illnesses. A person infected with the coronavirus is contagious to others for up to two days before symptoms appear, and they remain contagious to others for 10 to 20 days, depending upon their immune system and the severity of their illness.Д¬OVID-19 is diagnosed through a laboratory test. Symptoms show up in people within two to 14 days of exposure to the virus. What is the incubation period for COVID-19? Research continues, and more study may reveal how and why the coronavirus evolved to cause pandemic disease. In the past, several infectious disease outbreaks have been traced to viruses originating in birds, pigs, bats and other animals that mutated to become dangerous to humans. SARS-CoV-2 may have originated in an animal and changed (mutated) so it could cause illness in humans. 1, 2019, and the cause was a then-new coronavirus later named SARS-CoV-2. The first case of COVID-19 was reported Dec.

This is why mask-wearing, hand hygiene and physical distancing are essential to preventing COVID-19. Larger droplets may fall to the ground in a few seconds, but tiny infectious particles can linger in the air and accumulate in indoor places, especially where many people are gathered and there is poor ventilation. As of now, researchers know that the coronavirus is spread through droplets and virus particles released into the air when an infected person breathes, talks, laughs, sings, coughs or sneezes.