Department of Public Health Sciences (Dr. Mayo), Department of Family Medicine (Drs. Ellenbogen, Mendoza, and Russell), Department of Public Health Sciences and Nursing (Dr. Mendoza), and Center for Community Health and Prevention (Dr. Russell), University of Rochester School of Medicine and Dentistry, NY; Monroe County Department of Public Health, Rochester, NY (Dr. Mendoza) Nicole_Mayo@URMC.Rochester.edu
The authors reported no potential conflict of interest relevant to this article.
As such, long COVID is diagnosed primarily through a medical history and physical examination. The medical history provides a guide as to whether additional testing is warranted to evaluate for known complications of COVID-19, such as deep vein thrombosis, pulmonary embolism, myocarditis, and pulmonary fibrosis. As of October 1, 2021, a new International Classification of Disease (10th Revision) code went into effect for post COVID condition, unspecified (U09.9).7
The prevalence of long COVID symptoms appears to increase with age. Among patients whose disease was diagnosed using code U09.9, most were 36 to 64 years of age; children and adults ages 22 years or younger constituted only 10.5% of diagnoses.7 Long COVID symptoms might also be more prevalent among women and in people with a preexisting chronic comorbidity.2,7
Symptoms can be numerous, severe or mild, and lasting
Initially, there was no widely accepted definition of long COVID; follow-up in early studies ranged from 21 days to 2 years after initial infection (or from discharge, for hospitalized patients).8 Differences in descriptions that have been used on surveys to self-report symptoms make it a challenge to clearly summarize the frequency of each aspect of long COVID.
Long COVID can be mild or debilitating; severity can fluctuate. Common symptoms include fatigue, dyspnea or other breathing difficulties, headache, and cognitive dysfunction, but as many as 203 lasting symptoms have been reported.2,8-12 From October 1, 2021, through January 31, 2022, the most common accompanying manifestations of long COVID were difficulty breathing, cough, and fatigue.7 Long COVID can affect multiple organ systems,13,14 with symptoms varying by organ system affected. Regardless of the need for hospitalization initially, having had COVID-19 significantly increases the risk for subsequent death at 30 days and at 6 months after initial infection.15
The CDC reports that 20% to 25% of COVID-19 survivors experience a new condition that might be attributable to their initial infection.
Symptoms of long COVID have been reported as long as 2 years after initial infection.8 When Davis and colleagues studied the onset and progression of reported symptoms of long COVID,9 they determined that, among patients who reported recovery from COVID-19 in < 90 days, symptoms peaked at approximately Week 2 of infection. In comparison, patients who reported not having recovered in < 90 days had (1) symptoms that peaked later (2 months) and (2) on average, more symptoms (mean, 17 reported symptoms, compared to 11 in recovered patients).9