Coronaviruses are a large group of viruses that have been infecting humans for a very long time. They are named after the crown or the "corona" of spikes that is seen when the virus is looked at under a microscope.
Coronaviruses are quite common. And the various strains cause similar symptoms in humans, like cough, fever, headache, sore throat. They also spread easily from person to person.
What varies from strain to strain is their severity. One strain may cause a mild cold. While other strains—like COVID-19, SARS, AND MERS—can cause severe symptoms for certain people. This is especially true for people over age 65, or those with a weakened immune system or chronic medical conditions.
COVID-19 is a zoonotic disease, which means it was first in animals and then was transmitted to humans. SARS AND MERS also evolved from animals and then infected humans.
Scientists are trying to understand why COVID-19 is so dangerous. What they do know is that it can cause life-threatening complications like severe pneumonia and organ failure. So the risk of dying from COVID-19 is higher than it is for other more mild coronavirus strains.
COVID-19 is particularly difficult to control because most people have either mild or even no symptoms. And it can take up to 14 days for symptoms to appear. This is why self-isolation for two weeks is key. If too many people get sick at the same time, it will overwhelm our healthcare workers and hospitals. Slowing down the spread of COVID-19 is the most effective way to try to save lives.
The scientific understanding of COVID-19 as well as guidelines for its prevention and treatment are constantly changing. There may be new information since this article was published. It’s important to check with sources like the CDC for the most up-to-date information.