Long COVID
Long COVID or long-haul COVID is a group of health problems persisting or developing after an initial period of COVID-19 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 COVID-19 infection, but other agencies define it as starting at four weeks after the initial infection.
| Long COVID | |
|---|---|
| Other names | Long-haul COVID, post-COVID-19 syndrome, post-COVID-19 condition, post-acute sequelae of COVID-19 (PASC), chronic COVID syndrome |
| Symptoms | Highly varied, including post-exertional malaise (symptoms worsen with effort), fatigue, muscle pain, shortness of breath, chest pain and cognitive dysfunction ("brain fog") |
| Duration | Weeks to years, possibly lifelong |
| Causes | COVID-19 infection |
| Risk factors | Female sex, age, obesity, asthma, more severe COVID-19 infection |
| Frequency | 50–70% of hospitalised COVID-19 cases, 10–30% of non-hospitalised cases, and 10–12% of vaccinated cases |
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, loss of smell or taste, muscle weakness, fever, and cognitive dysfunction may also present. Symptoms often get worse after mental or physical effort, a process called post-exertional malaise. There is a large overlap in symptoms with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).
The causes of long COVID are not yet fully 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.
Estimates of the prevalence of long COVID vary based on definition, population studied, time period studied, and methodology, generally ranging between 5% and 50%. Prevalence is less after vaccination. Risk factors are higher age, female sex, having asthma, and a more severe initial COVID-19 infection. As of 2023, there are no validated effective treatments. Management of long COVID depends on symptoms. Rest is recommended for fatigue and pacing for post-exertional malaise. People with severe symptoms or those who were in intensive care may require care from a team of specialists. Most people with symptoms at 4 weeks recover by 12 weeks. Recovery is slower (or plateaues) for those still ill at 12 weeks. For a subset of people, for instance those meeting the criteria for ME/CFS, symptoms are expected to be lifelong.