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By Mayo Clinic Staff

Many people with COVID-19, also called coronavirus disease 2019, recover at home. But for some, the illness can lead to hospital care, treatment in the intensive care unit or death.

Not every risk factor for serious COVID-19 illness is known, but some are clear. Age and having chronic health conditions both raise your risk, for example. Other factors may include where you live, work or learn. Access to medical care also may affect risk. Having more than one risk factor makes the risk of serious illness even higher.

If any of these risk factors apply to you, and you have symptoms of COVID-19, act quickly and talk with your healthcare team about treatment options. Medicine to treat the illness works best if started right away.

People age 65 and older and babies younger than 6 months have a higher than average risk of serious COVID-19 illness. Those age groups have the highest risk of needing hospital care for COVID-19.

Babies younger than 6 months aren't eligible for the COVID-19 vaccine, which adds to their risk. Older people may be more at risk because the immune system may be less able to clear out germs. Medical conditions that raise the risk of serious COVID-19 also become more likely with age.

Serious COVID-19 illness is more likely for people who have other health issues.

Some common health conditions linked to aging are:

• Heart disease. Examples are heart failure or coronary artery disease.
• Diabetes. The risk is higher for both type 1 and type 2.
• Chronic lung diseases. This includes conditions that damage lung tissue.
• Overweight or obesity. The risk goes up with overweight or obesity measured by body mass index, also called BMI.
• Chronic kidney disease. This is especially true if you are on dialysis.

These conditions become more common as people age. But they can affect people of any age. The risk of serious COVID-19 illness is linked to having one or more underlying medical conditions.

The risk of serious COVID-19 illness is higher if you have lung disease. Examples include tuberculosis, cystic fibrosis, interstitial lung disease, bronchiectasis and COPD, which stands for chronic obstructive pulmonary disease. Other lung conditions, such as a history of pulmonary hypertension, affect a person's risk of serious illness after COVID-19.

In general, having cancer can raise the risk of serious COVID-19 illness. People who have blood cancer may have a higher risk of being sick for longer, or getting sicker, with COVID-19 than people with solid tumors. This also is true of people who had blood cancer in the past.

Cancer treatment also may affect how well your COVID-19 vaccine works. Ask your care team about getting vaccinated after treatments that affect some immune cells.

If an organ or body system is already weakened by disease, infection with the COVID-19 virus can cause further damage. In other cases, medicine for another condition can lower the immune system's response to the virus that causes COVID-19.

Many different diseases can raise the risk of severe COVID-19 illness.

• Brain and nervous system diseases, such as stroke.
• Chronic liver disease, specifically cirrhosis, metabolic dysfunction-associated liver disease (MASLD) and autoimmune hepatitis.
• HIV that is not well managed with medicine.
• Heart disease, including congenital heart disease and cardiomyopathies.
• Mood disorders or schizophrenia.
• An organ or stem cell transplant.
• Blood disorders such as sickle cell anemia and thalassemia.

Other risk factors for severe COVID-19 are:

• Smoking.
• Pregnancy or having recently given birth.
• Use of medicines that lower the immune system's ability to respond to germs.

Also, as a general group, people with complex medical needs may be at higher risk. Examples include people with cerebral palsy and people with genetic or metabolic syndromes.

These are not the only conditions that increase the risk of severe COVID-19. Talk with your care team if you have questions about your risk.

The COVID-19 vaccine can lower the risk of death or serious illness caused by COVID-19. Your healthcare team may suggest added doses of COVID-19 vaccine if you have a moderately or seriously weakened immune system.

Besides vaccination, there are other ways to stop the spread of the virus that causes COVID-19.

In addition to COVID-19 vaccination, make it a habit to:

• Test for COVID-19, especially if you have symptoms. Also, test five days after coming into contact with the virus even if you do not have symptoms.
• Try to spread out in crowded public areas. This is especially important in places with poor airflow and if you have a higher risk of serious illness. If possible, try to keep air flowing when you're inside.
• Wear a mask when you're inside a crowded place with poor airflow. This is most important when many people in the area are sick with COVID-19. Masks are most effective if they fit the face closely.
• Stay apart from people who have symptoms or who are sick. Avoid close contact with anyone who is sick or has symptoms, if possible.
• Wash your hands often and wash them well with soap and water for at least 20 seconds. Or use an alcohol-based hand sanitizer with at least 60% alcohol.
• Cover your coughs and sneezes. Cough or sneeze into a tissue or your elbow. Then wash your hands.
• Clean and disinfect high-touch surfaces. For example, clean doorknobs, light switches, electronics and counters regularly.

These basic actions are even more important for people who have weakened immune systems and their caregivers.

There is one medicine that may be used to prevent COVID-19 in people with weakened immune systems. It is a monoclonal antibody called pemivibart (Pemgarda). But this medicine does not treat an active infection.

People can take other actions based on their risk factors.

• If you're at a higher risk of serious illness, ask your care team about ways to protect yourself. Know what to do if you get sick so you can quickly start treatment.
• Lower your risk of COVID-19 complications by making sure that any health issues are well managed. This includes staying on track with managing medical conditions, going to all medical appointments and planning ahead to avoid running out of medicine. Keep taking medicines as suggested by your healthcare team.
• Stay up to date on vaccines. This includes vaccines for flu, pneumonia and respiratory syncytial virus (RSV). These vaccines won't prevent COVID-19. But becoming ill with a respiratory illness may worsen your outcome if you also catch COVID-19.

Also, consider making a care plan. Write down your medical conditions, medicines, special food or diet needs, care team members, and emergency contacts.