The coronavirus that causes COVID-19 can cause mild to more severe respiratory illness. Symptoms include fever, cough, and difficulty breathing. In a small proportion of patients, COVID-19 can cause complications, including death, particularly among those who are older or who have chronic medical conditions. Symptoms appear within 14 days of being exposed to an infectious person. COVID-19 spreads primarily through respiratory droplets produced when an infected person coughs or sneezes.