Covid damages cells and organs in ways that can cause dozens, even hundreds, of symptoms — or none at all. Even those who aren’t suffering today may still develop brain, heart, liver, and other diseases months or years later due to damage from Covid.

Others who are suffering may be reluctant to seek treatment for — or even admit to having — a disease associated with reduced mental and physical fitness. Some keep their illness to themselves and choose not to tell their friends, family, or healthcare providers, especially with so many still openly questioning whether Long Covid is “real.” We don’t know the full extent of how many are struggling with this illness in its many forms, and estimates vary dramatically because of:

1. Lack of agreement on how to define Long Covid

2. Long Covid’s wide range of symptoms and severities

3. The challenges in testing for all the ways Covid can damage our long-term health

Here, we present some of the estimates researchers have come up with for the most common and obvious symptoms, while other sections help us better understand the likelihood of specific health risks with links to Covid infection.