Most people confirmed to have MERS-CoV infection have had severe respiratory illness with symptoms of:

• fever
• cough
• shortness of breath

Some people also had diarrhea and nausea/vomiting. For many people with MERS, more severe complications followed, such as pneumonia and kidney failure. About 3 or 4 out of every 10 people reported with MERS have died. Most of the people who died had a pre-existing medical condition that weakened their immune system, or an underlying medical condition that hadn’t yet been discovered. Medical conditions sometimes weaken people’s immune systems and make them more likely to get sick or have severe illness.

Pre-existing conditions among people who got MERS have included

• diabetes
• cancer
• chronic lung disease
• chronic heart disease
• chronic kidney disease

Some infected people had mild symptoms (such as cold-like symptoms) or no symptoms at all.

The symptoms of MERS start to appear about 5 or 6 days after a person is exposed, but can range from 2 to 14 days.