Thousands of Covid-19 patients continue to suffer serious, debilitating and lingering symptoms many months after their initial bout of infection, with major social, health and economic consequences, European health experts said on Thursday.

Publishing a World Health Organization-led guidance report on the condition, often referred to as "long Covid" or "post-Covid syndrome", experts said around one in 10 Covid-19 patients are still unwell 12 weeks after their acute infection, and many suffer symptoms for far longer...