What Is Long COVID? Understanding an Often Misunderstood Condition
Long COVID Doesn’t Always Look the Way People Expect
Long COVID is a complex condition that can affect multiple body systems. Partly because of this, symptoms don’t always seem connected to each other, and two people with Long COVID can have very different experiences.
Some of us realize right away that our health problems are connected to a recent COVID infection. Others may struggle for months or even years before recognizing the connection.
Similar ongoing health challenges can also appear following a COVID vaccine. We’ll talk more about vaccine injury and how it relates to Long COVID later in this article.
In this article, we’re going to start with the basics: what Long COVID is, when ongoing health problems are considered Long COVID, where vaccine injury fits into the conversation, and what we know about how many people are affected. Then, in next week’s article, we’ll take the next step and look at what Long COVID can look like, including some of the most common symptoms and related health conditions.
When Does It Become Long COVID?
One of the confusing things about Long COVID is figuring out when ongoing health problems actually become Long COVID. You may have seen different answers depending on where you looked, partly because the definition has changed as our understanding of the condition has grown.
For this article, I’m using the 2024 consensus definition from the National Academies of Sciences, Engineering, and Medicine (NASEM). It defines Long COVID as an infection-associated chronic condition that occurs after a SARS-CoV-2 (COVID) infection and is present for at least three months. It can affect one or more systems in the body and may be continuous, relapsing and remitting, or progressive.
In everyday language, that means Long COVID doesn’t have to follow one particular pattern. Your health problems may have started with your original COVID infection and never completely gone away. Symptoms can also improve significantly, or even seem to disappear for a while, and then return. You may also develop new symptoms or health problems later, or find that your health gradually changes or worsens over time.
And you didn’t have to be seriously ill with COVID for this to happen. Long COVID can develop after an asymptomatic, mild, or severe infection. So if you find yourself thinking, “But my COVID wasn’t that bad,” that doesn’t rule out Long COVID.
What About COVID Vaccine Injury?
Long COVID and vaccine injury are medically distinct. Long COVID follows a COVID infection, while vaccine injury follows a vaccination. But having different triggers doesn’t mean the health challenges people experience are completely different. There can be significant overlap in symptoms.
Many people, myself included, have health problems that stem from both an infection and a vaccine. When that happens, it isn’t always possible to distinguish which symptoms or health problems are connected to which event.
The important thing I want you to take with you from this discussion is that, regardless of where our health problems began, many of us face the same challenges when it comes to understanding what is happening in our bodies and learning how to manage our health.
How Common Is Long COVID?
This is not an easy question to answer, and all of the numbers we have are estimates. There are a lot of reasons for this. Long COVID definitions and research methods have changed, not all COVID infections have been documented, testing and surveillance have decreased, and reinfections make it even more difficult to determine how many people are affected. Long COVID also looks different from person to person, which can make it difficult to recognize and track.
I also believe there is another group that is very difficult to count: people who are dealing with new or worsening health challenges but don’t realize there may be a connection to a previous COVID infection. Long COVID still isn’t something that is widely discussed or always recognized, so it may not occur to someone to look back at when their health began to change. That means the true number of people affected may be even more difficult to determine.
The World Health Organization currently estimates that about 6% of people who have a symptomatic COVID infection develop Long COVID. That may not sound like a huge number at first, but 6% is about 1 in every 17 people who have a symptomatic infection.
Here in the United States, CDC data from 2023 found that 6.4% of adults were experiencing Long COVID at the time they were surveyed. That’s about 1 in every 16 adults. To put that into perspective, applying that percentage to the U.S. adult population in 2023 works out to roughly 16.8 million adults. That’s a lot of people trying to make sense of health problems that may have changed nearly every part of their lives.
The numbers will continue to change. The virus that causes COVID is still with us, and people continue to be infected and reinfected.
Where Do We Go From Here?
Long COVID is common, complex, and still often misunderstood. It can develop after an infection that seemed relatively minor at the time, and it doesn’t always follow a neat or predictable pattern. Simply understanding that can be an important first step in making sense of changes in your health.
But understanding what Long COVID is is only the beginning. With so many different symptoms and health conditions associated with Long COVID, recognizing what it can actually look like can be much more difficult.
That’s where we’re going next. In next week’s article, “What Does Long COVID Look Like? Symptoms and Related Conditions,” we’ll look at some of the symptoms and health conditions commonly associated with Long COVID and explore how health problems that may seem completely unrelated can sometimes be pieces of a much bigger picture.
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Sources & Further Reading
World Health Organization (2026). WHO COVID-19 Global Risk Assessment — Version 10.
