This November, the Supreme Court will consider the constitutionality of the Affordable Care Act (ACA). Eighteen state attorneys general and the White House argue that the law’s requirement that people have health insurance is unconstitutional. The Court will decide whether the mandate can stand and, if not, whether to strike down all or part of the ACA.

A key provision of the health law the Court might target is one preventing insurance companies from denying coverage to people with preexisting health conditions, refusing to cover those conditions, or charging exorbitant prices for coverage. If this part of the law is struck down, insurers could once again reject applicants, only partially cover them, or charge them more.

The loss of insurance coverage because of a preexisting condition would be especially painful for many Americans during this pandemic. People could be denied coverage if they had a previous COVID-19 infection, experience anxiety or depression related to COVID-19, or work in a job that places them at higher risk for infection. So far, the pandemic has killed more than 210,000 Americans, and it may result in millions of hospitalizations as well as lasting health consequences for “long-haulers.”

Prior to the pandemic, as many as 133 million people under age 65, including 116 million adults ages 18 to 64, were estimated to have one or more preexisting conditions. If insurers are allowed to designate COVID-19 infection as preexisting, how many additional adults could potentially become uninsurable? More than 7 million people have already been infected by COVID-19 in the U.S. However, those 7 million cases include children as well as older adults eligible for Medicare, which covers all preexisting conditions. Moreover, some nonelderly adults already had preexisting conditions like hypertension, obesity, or diabetes prior to infection with COVID-19.

Projecting the Rise in Adults with COVID-19 as a Preexisting Condition

We used data from the Centers for Disease Control and Prevention’s (CDC) COVID-19 database and Johns Hopkins University to calculate how many adults under age 65 with COVID-19 and no prior reported preexisting condition there are in the U.S., and how many more there might be by the end of 2020. For this population, COVID-19 would be their first preexisting condition. (See here to learn more about our study methods.)

As of October 7, 7.5 million U.S. residents were confirmed to have been infected by COVID-19. We estimate that the pandemic has already added approximately 3.4 million nonelderly adults to the millions of Americans with preexisting conditions. If the current pace of approximately 45,000 new daily cases continues, COVID-19 itself will add more than 20,000 nonelderly adults each day.

As the Supreme Court weighs whether to strike down the ACA in its entirety, including its protections for people with preexisting conditions, the COVID-19 pandemic is adding many thousands of Americans to the group of who may be unable to get or afford insurance coverage. The pattern of pandemic spread will determine the exact number, but a reasonable rule of thumb is that approximately half of all new COVID-19 infections will occur among relatively healthy nonelderly adults without a known preexisting condition.

This may be conservative, however. COVID-19 is increasingly spreading among younger adults, who are less likely to have a preexisting condition. According to CDC data, only 23 percent of adults ages 20 to 29 with COVID-19 have a known condition. Data from the National Health Interview Survey similarly suggest that just 18 percent of adults ages 18 to 34 have a condition. Unlike the early days of the pandemic when testing was very limited, testing is increasingly identifying the roughly 40 percent of adults who are infected but have no symptoms.

How Will Insurers React to an Upending of the ACA?

In light of uncertainty about the long-term effects of COVID-19, it seems likely that insurers will designate COVID-19 as a preexisting condition. Prior to the ACA, some infectious diseases, such as influenza, were not counted as preexisting conditions. But other diseases were, especially those with long-term consequences like HIV.

Influenza is not comparable to COVID-19. COVID-19 carries higher risks of hospitalization and adverse health consequences. Even for people with asymptomatic infections, there may be long-term effects on the heart, lungs, and immune system, just as the hepatitis C virus causes silent infection but long-term liver damage for some people. Lacking data on COVID-19’s long-term effects, actuaries will find it difficult to project future expenses, making its exclusion from coverage attractive to insurers.

A decision to overturn the ACA’s preexisting condition provisions could not come at a worse moment. In a time when mounting job losses are closing off access to employer-based insurance, it threatens to put the health coverage, and health, of an expanding number of Americans in jeopardy, including groups in society that have historically faced greater health and financial challenges.

In the pre-ACA world, many people avoided health care to avoid being labeled with a preexisting condition that might threaten their insurance or force them to pay higher premiums. If we return to those days, healthy people might avoid COVID-19 testing altogether. And that is exactly the opposite of what must happen if we are ever to get this pandemic under control.