The “natural history of disease” is what scientists call the timeline from the moment a person is exposed to a disease until they are no longer sick. We still have a lot to learn about COVID-19, but we have a general idea of what its natural history looks like.
After COVID-19 infection, most people will experience symptoms within five days, though a small number of people will be symptom-free for two weeks or more. During this time, you may not know you are sick, but you can still pass the disease to others. This is called the subclinical phase of the disease.
Once you start to have symptoms, you have entered the clinical phase. Symptoms vary between people, but the largest study to date found that 87% of COVID-19 patients had a fever, 58% had a cough, 38% experienced difficulty breathing, 36% endured muscle aches or fatigue, and 31% felt chest tightness. Less commonly, patients have also reported headaches and diarrhea.
We don’t yet have great data about how long the illness lasts for people with mild cases, but doctors at Johns Hopkins University say that most people appear to recover one to two weeks after symptoms start. Studies among people who have been hospitalized with COVID-19 suggest that the road to recovery might be three or four weeks (or even longer) for these more serious cases.
While you are recovering, you may still be able to get others sick. When tests find the genetic material of the virus in the body, we say that the person is “shedding” the virus. This is often used as a marker of whether a person can spread the virus. In general, viral shedding is highest at the beginning of symptoms and decreases as symptoms improve. One study of the novel coronavirus reports that shedding lasted for, on average, 20 days after the onset of symptoms, but one patient shed the virus for 37 days. You can even shed the virus after all of your symptoms are gone. This is why the CDC says that you should consider yourself contagious for 72 hours after your symptoms disappear and stay away from others during that period to avoid spreading the virus.
Last updated: April 14, 2020, 9:50 am
Science review: AHN, GSN