Post-COVID conditions (PCCs) are a collection of prolonged symptoms identified in individuals recovering from SARS-CoV-2 infection or COVID-19 disease. The US Centers for Disease Control and Prevention (CDC) describes PCCs as new, returning, or ongoing health problems 4 or more weeks after COVID-19, even in those who did not have COVID-19 symptoms initially. Other terms for PCCs are long COVID, long-haul COVID, postacute COVID-19, long-term effects of COVID-19, or chronic COVID-19. Per the CDC, in 2022, 6.9% of US adults reported ever experiencing long COVID.

Most commonly, patients may experience fatigue, generalized weakness, brain fog, and dyspnea, but symptoms can include arthralgias, myalgias, cough, chest discomfort, palpitations, anosmia, dysgeusia, nausea, abdominal pain, diarrhea, headache, poor sleep, difficulty concentrating, memory impairment, depression, and anxiety. Postural orthostatic tachycardia syndrome (POTS) is a frequent occurrence.

As more is learned about the long-term effects of COVID-19 in some individuals, durable cutaneous manifestations have been observed. See skin and oral mucosal manifestations of COVID-19.

A preprint (not yet peer-reviewed) prospective longitudinal cohort study in the United Kingdom analyzed 336 652 subjects who tested positive for SARS-CoV-2. Of these, 9323 subsequently developed long COVID, defined as symptoms lasting for more than 28 days, and 1459 had post-COVID syndrome, defined as more than 12 weeks of symptoms. Review of symptom clusters in these subjects identified 3 main clusters of syndromes occurring within and across wild-type, delta, and alpha variants. (It is thought that the SARS-CoV-2 omicron variant is much less likely to lead to long COVID compared with the original, wild-type virus.) These clusters are cardiorespiratory, central neurologic, and multiorgan symptoms; a lesser cluster of gastrointestinal symptoms was also noted. Other researchers have clustered into main categories of cardiorespiratory syndrome, fatigue syndrome, and neuropsychiatric syndrome, with lesser clusters of gastrointestinal syndrome and hepatobiliary syndrome.

Symptoms can persist beyond 6 months in some individuals, although patients most often progressively improve with time. Eventually, most patients report returning to their usual state of health. A population-based cohort study of over 3000 patients found that fatigue and cognitive dysfunction were common sequelae after SARS-CoV-2 infection, with many of these symptoms improving over 2 years.

The pathophysiology of PCCs is still unknown. There are no specific laboratory abnormalities or imaging findings necessary for the diagnosis of PCCs.

PCCs can develop regardless of initial COVID-19 illness severity. Risk factors include older age, partial or no vaccination, female sex, more than 5 symptoms in the first week of acute infection, and comorbid illness, such as diabetes and chronic kidney disease.

In a large study, about one-fifth of fully vaccinated patients diagnosed with breakthrough infection reported having long-COVID symptoms at 6 weeks after diagnosis. Another published study found that vaccination was protective against development of PCCs; those who were fully vaccinated when they contracted SARS-CoV-2 developed PCCs at approximately half the rate of those who were unvaccinated when they contracted SARS-CoV-2 (5.2% versus 10.7%, respectively). In a population-based probability sample of 4695 adults with COVID-19, long COVID prevalence was 40%-60% lower among adults vaccinated (vs. unvaccinated) prior to their COVID-19 onset.

Pediatric patient considerations: Data from the CDC suggest that the prevalence of long COVID is around 1%-2% of children who have had COVID-19, although some estimates have been as high as 10%-20%. The most frequently reported symptoms in children include fatigue, brain fog, and headaches; however, symptoms affecting virtually all body systems have been described. In severe cases, some children may experience respiratory and cardiovascular problems (including myocarditis). An increased rate of new-onset type 1 and type 2 diabetes mellitus as well as more severe episodes of diabetic ketoacidosis have also been observed. Special attention should be paid to patients with preexisting intellectual or developmental disabilities as well as those who have a complex medical history, as new symptoms and conditions may be overlooked. 

Related topics: multisystem inflammatory syndrome in adults (MIS-A), multisystem inflammatory syndrome in children (MIS-C)