How many people in the U.S. have developed "long COVID"? It could be in the range of 7.7–23 million, some estimates say. We discuss what is and isn't known about long COVID—new, returning, or ongoing health problems 4 or more weeks after an initial case of COVID-19. For example, some people with the condition experience chronic fatigue and have to stop working, which can affect their income and health insurance. But other economic effects are still unclear. The federal government is taking steps to fund more research and help affected people. We describe challenges it could encounter and provide questions for policymakers to consider.