Of the nearly 24 million adults in the U.S. who currently have long COVID, more than 80% are having some trouble carrying out daily activities, according to CDC data released Wednesday.

Why it matters: Nearly three years into a pandemic that has left millions newly disabled, medical researchers continue to search for an effective treatment.

The big picture: Long COVID symptoms can include shortness of breath, cognitive difficulties and symptoms that worsen even with minimal physical or mental effort — a primary indicator of chronic fatigue syndrome.

• The pandemic sharpened the focus on the once largely dismissed area of chronic fatigue in health care, but misunderstandings and stigma persist.
• Up to 4 million people are estimated to be out of work because of long COVID symptoms, according to a Brookings Institute report in August.
• While long COVID is classified as a disability, qualifying for Social Security benefits requires proof that the condition has or will last a year, even though there's no test to diagnose long COVID, per CDC.

By the numbers: Between Sept. 14 and Sept. 26, more than one in four adults with long COVID reported significant limitations on day-to-day activities, per the CDC data.

• The number jumps closer to 40% for respondents who are Black, Latino or disabled — three groups that shouldered outsized burdens throughout the pandemic.
• Nearly 30% of adults previously infected with COVID reported having long COVID at some point, but the percentage is higher for transgender people, disabled Americans and those without a high school diploma, according to Wednesday's report.

The CDC data is limited to adults and doesn't cover whether a respondent with long COVID is unvaccinated or whether their bout of the virus was severe — two factors the CDC states heightens the risk of getting long COVID.

Yes, but: The agency's report also confirms that people are developing long COVID symptoms regardless of age, race, gender or previous disability.

• In CDC's previous study, which found that one in five adults developed chronic conditions possibly stemming from having coronavirus, researchers concluded that prevention strategies will be critical to reducing the magnitude of post-COVID.
• While HHS and the Biden administration have pledged help, most federal COVID mandates have been lifted, making vaccinations a major line of defense.

The bottom line: As winter months near, an expected rise in cases coupled with fewer COVID protections could mean millions more will get long COVID — and there's little to no safety net in place to help them.

Go deeper: Axios AM Deep Dive: Long COVID crisis