The United States Centers for Disease Control and Prevention (CDC) have updated and expanded their list of people at risk of severe illness. Instead of marking a firm threshold for age related risk, the CDC now notes that risk "increases steadily as you age, and it's not just those over the age of 65 who are at increased risk for severe illness." Recently published data shows that the greater your age the higher your risk for severe illness. The list of underlying medical conditions which increase risk was also expanded. According to research done by the CDC, there is "consistent evidence (from multiple small studies or a strong association from a large study) that specific conditions increase a person's risk of severe COVID-19 illness" including:
Other illnesses such as asthma, hypertension, dementia, cerebrovascular disease and pregnancy were added to the list of conditions that may increase a person's risk of severe illness. More information can be found here.