When flu season arrives or a respiratory virus like COVID-19 circulates, public health guidance often singles out people with "underlying conditions" as being at higher risk. But many people don't know whether they have one. Some of the conditions that raise risk the most — heart disease, lung disease and certain cancers — can be present for years without symptoms.

This article explains which conditions are commonly linked to more severe respiratory illness and why understanding your own health status can help you plan ahead.

Key Points

• Health agencies such as the CDC identify heart disease, chronic lung disease, cancer, and chronic kidney and liver disease as conditions that can raise the risk of severe respiratory illness.
• Several of these conditions can develop without noticeable symptoms.
• Knowing your health status can inform conversations with your doctor about vaccines and precautions.
• Vaccine eligibility and recommendations change over time, so check current guidance from the CDC or your state health department.

Why Underlying Conditions Matter

Respiratory viruses tend to hit hardest in people whose bodies are already managing another health problem. Conditions affecting the heart, lungs, kidneys or liver can make it harder to recover from infection and increase the likelihood of hospitalization.

Lung conditions

Because viruses like influenza and COVID-19 primarily target the lungs, existing lung problems — such as chronic obstructive pulmonary disease (COPD) or lung cancer — can raise the risk of serious illness. CT imaging can reveal signs of these conditions; see the lung scan overview.

Heart conditions

Heart failure, coronary artery disease, cardiomyopathy, pulmonary hypertension, congenital heart disease and high blood pressure are all associated with higher risk. Coronary artery disease in particular can progress silently; a heart scan measures plaque in the coronary arteries.

Kidney and liver disease

According to the Mayo Clinic, chronic kidney or liver disease can also increase the chance of becoming seriously ill. A body scan covering the abdomen includes the kidneys and liver.

Using This Information

Knowing whether you have an underlying condition can help you and your physician make informed decisions about:

• Which vaccines are recommended for you and when
• Precautions during peak respiratory illness seasons
• Managing existing conditions to reduce overall risk

Current vaccine recommendations are published by the CDC and state health departments, including the Oklahoma State Department of Health and the Texas Department of State Health Services. Your doctor can help you apply that guidance to your situation.

The Takeaway

Many people learn they have heart or lung disease only after a serious illness. Understanding your health ahead of time — through regular checkups and, for some, preventive imaging — puts you in a better position to protect yourself when respiratory viruses are circulating.