A preexisting condition usually refers to a health issue you had before the date new health coverage starts. People may also use it to refer to health conditions you had before a new one began.

Since the Affordable Care Act (ACA) went into effect in 2014, insurance companies offering comprehensive coverage in the United States can no longer:

  • deny coverage to individuals with preexisting health conditions
  • charge people with preexisting health conditions higher premiums
  • deny claims based on preexisting conditions

People may also use the term “preexisting health condition” or “underlying health condition” to refer to conditions that increase the risk of severe illness related to COVID-19.

Between 48% and 86% of Americans ages 55 to 64 years have a preexisting condition, as do 19% to 50% of Americans age 54 years and younger. Between 15% and 30% of people without a preexisting condition will likely develop one in the next 8 years.

Keep reading to learn what health conditions are considered preexisting conditions and how having one may affect your risk of severe illness from COVID-19.

With few exceptions, health insurance in the United States cannot deny you coverage for a preexisting condition.

Before 2014, health insurance plans in the United States could charge more or deny coverage or claims based on preexisting conditions. According to 2022 research, preexisting health conditions that could be used to deny coverage included:

A family could receive a denial for insurance coverage if at least one member had at least one preexisting condition.

Some insurance plans may still be able to deny coverage. These include:

Medigap plans may deny coverage or charge higher costs based on preexisting conditions if you do not enroll during your open enrollment window. This is because they do not meet the ACA’s definition of minimal essential coverage.

Typically, when you turn 65 and sign up for Medicare Part B, you have a 6-month open enrollment period for Medigap. During this window, you can enroll in any Medigap policy without the insurance company needing medical underwriting, which means insurers can’t refuse coverage due to preexisting conditions.

After that window closes, Medigap insurers can charge higher costs or deny coverage. If you’re under 65 and qualify for Medicare due to a disability, Medigap insurers may not be legally required to ensure you until you turn 65 and enter the open enrollment window.

Note that state protections may differ from federal requirements.

Certain preexisting health conditions can increase the risk of severe outcomes with COVID-19, including long COVID. These may include:

COVID-19 vaccine access

According to a 2025 update to the COVID vaccine guidelines, the CDC recommends COVID boosters for people with some of these underlying health conditions, but not all of them. Recent changes may limit access to booster shots for some people, including those with preexisting conditions, depending on where they live.

It may be possible for a healthcare professional to prescribe the vaccine or booster off-label, which may allow you to get the vaccine at a healthcare professional’s office. However, it may not be covered by your insurance in this instance. It’s best to check with your insurance plan before getting a booster.

A preexisting health condition refers to a health condition you have had before a new insurance plan began or before another health condition began.

It typically includes health conditions like diabetes, asthma, heart disease, and cancer.

Which conditions are considered preexisting for a specific purpose can vary.