Long COVID

Long COVID or long-haul COVID is a group of health problems persisting or developing after an initial period of COVID‑19 from SARS-CoV-2 infection. Symptoms can last weeks, months, or years and are often debilitating. The World Health Organization defines long COVID as starting three months after the initial disease, but other agencies define it as starting at four weeks after the initial COVID-19. Long COVID is characterised by a large number of symptoms that sometimes disappear and then reappear. Commonly reported symptoms of long COVID are fatigue, memory problems, shortness of breath, and sleep disorder. Several other symptoms, including headaches, mental health issues, initial loss of smell or taste, muscle weakness, fever, and cognitive dysfunction ("brain fog") may also present. Symptoms often get worse after mental or physical effort, a process called post-exertional malaise (PEM). There is a large overlap in symptoms with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The causes of long COVID are not understood. Hypotheses include lasting damage to organs and blood vessels, problems with blood clotting, neurological dysfunction, persistent virus or a reactivation of latent viruses and autoimmunity. Diagnosis of long COVID is based on (suspected or confirmed) COVID‑19 infection or symptoms—and by excluding alternative diagnoses. Many of the symptoms attributed to long COVID are non-specific and occur in other conditions, which makes it difficult to know the true prevalence of long COVID. As of 2025, the prevalence of long COVID is estimated to be about 6–7% in adults, and about 1% in children. Prevalence might be reduced after vaccination. Risk factors include but are not limited to higher age, female sex, having asthma, and a more severe initial COVID‑19 infection. Anyone can develop long COVID. As of 2025, there are no validated effective treatments. Management of long COVID depends on symptoms. Rest is recommended for fatigue...