A survey of half a million adults in England suggests around two million people may have had some long-lasting symptoms after having coronavirus - sometimes known as "long Covid".The React study shows about a third of people who report they have coronavirus symptoms have one or more symptoms that persist for at least 12 weeks.
Researchers say managing the long-term consequences are a "major challenge".
The government has provided £50m for research into long Covid.
Long Covid is an emerging phenomenon that is not yet fully understood, and there is no universally-agreed definition.
It covers a broad range of symptoms after an initial Covid infection, including fatigue, coughs, chest pain, headaches and muscle pain.During the study, which took place between September 2020 and February 2021, a random sample of people were asked whether they had had Covid-19 (confirmed or suspected), and about the presence and duration of 29 different symptoms.
Higher weight, smoking, lower incomes, having a chronic illness and being hospitalised with Covid were linked to a higher chance of experiencing long-lasting symptoms.