Despite the dramatic reduction in new COVID-19 cases, the number of people in the U.S. contending with long COVID-19 remains steady, at around 17 million people in March 2024. And overall, it affects about 30% of those who contract COVID-19, whether it's mild or severe.

According to the National Academies of Sciences, Engineering, and Medicine, there are more than 200 symptoms of long COVID, including brain fog, fatigue, aches, pains, loss of smell/taste, and many other discomforts.

That's a lot to wrangle into a definition of what, exactly, long COVID is. But they’re trying.

In their new proposal, they say it is "an infection-associated chronic condition that occurs after COVID-19 infection and is present for at least three months as a continuous, relapsing and remitting, or progressive disease state that affects one or more organ systems."

It can affect kids and adults, make coexisting conditions worse, create new ones, and appear weeks or months after infection. Sometimes it goes away in months, but sometimes it takes years.

Causes of long COVID symptoms might include tiny blood clots, inflammation (especially of blood vessels), autoimmune conditions, viral persistence, reactivation of infections you've had previously, and emotional consequences of hospitalization for COVID-19.

Treatment depends on identifying what bodily systems long COVID is affecting and addressing those issues.

But the best ways to reduce your risk of long COVID-19 is to be vaccinated and practice good prevention with hand washing, using masks when appropriate, and adopting healthy lifestyle habits.