As the outbreak of novel coronavirus COVID-19 continues to expand as well as as testing capacity in the U.S. increases, CDC expects more cases to be detected across the country. This includes more instances of person-to-person spread in more states. While information so far suggests that most COVID-19 illness is mild, report out of China suggests serious illness occurs in 16% of cases. Older people and people with certain underlying health conditions like heart disease, lung disease and diabetes, for example, seem to be at greater risk of serious illness.