City University of New York (CUNY) researchers estimate that 7.3% of US adult COVID-19 survivors have persistent symptoms—or almost 19 million Americans. Studies in India and Denmark, meanwhile, report rates of 29.0% and 25.0%, respectively.
Symptoms appear to improve with time
The CUNY team surveyed a random sample of 3,042 adults weighted to 2020 US Census data from Jun 30 to Jul 2, 2022. The results were published today in Clinical Infectious Diseases.
An estimated 7.3% of respondents reported long-COVID symptoms, a figure corresponding to about 18.8 million adults, the investigators wrote. A quarter (25.3%) of adults reporting long COVID said that their symptoms affected their ability to complete daily activities "a lot," 44% said they were last had COVID-19 in the last 6 months, 27% said 6 to 12 months earlier, and 29% said it had been more than a year.
In models adjusted for age and sex, long COVID was more common among women than men (adjusted prevalence ratio [aPR], 1.84) and in those with underlying illnesses (versus none) (aPR, 1.55), those who didn't receive a COVID-19 vaccine booster (versus boosted) (aPR, 1.67), and the unvaccinated (versus boosted) (aPR, 1.41).
Long COVID was less common among respondents aged 65 or older than among younger people (aPR, 0.43) and in Black versus White (aPR, 0.60), Hispanic versus White (aPR, 0.57), and Asian/Pacific Islander versus White (aPR, 0.44).
"We observed a high burden of long COVID, substantial variability in prevalence of SARS-CoV-2 and risk factors unique from SARS-CoV-2 risk, suggesting areas for future research," the study authors wrote. "Population-based surveys are an important surveillance tool and supplement to ongoing efforts to monitor long COVID."
Severe infection a risk factor
Yesterday in PLOS One, researchers from the All India Institute of Medical Sciences described their study of 858 adult COVID-19 survivors who were followed for a median of 44 days (487 patients) or 223 days (371) after infection.
A total of 29.2% and 9.4% of participants reported long-COVID symptoms at 4 weeks and 6 months of follow-up, respectively. Among the 415 participants who had been mildly or moderate ill, 23.4% reported long COVID at 4 weeks, compared with 62.5% of the 72 who had severe or critical infections.
At 6 months, the incidence of long COVID among the 319 patients with mild or moderate illness was 7.2%, compared with 23.1% in the 52 who had been severely or critically ill.
Fatigue was the most common long-COVID symptom. Risk factors for long COVID at 4 weeks included underlying medical conditions (adjusted odds ratio [aOR], 2.00), more symptoms during infection (aOR, 11.24), receipt of two doses of COVID-19 vaccine (aOR, 2.32), more severe infection (aOR, 5.71), and hospital admission (OR, 3.89).
In India, at 6 months, the incidence of long COVID among the 319 patients with mild or moderate illness was 7.2%, compared with 23.1% in the 52 who had been severely or critically ill.
"A considerable proportion of COVID-19 cases reported Long COVID symptoms," the researchers wrote. "More research is needed in Long COVID to objectively assess the symptoms and find the biological and radiological markers."
Poorer general health, loss of taste and smell
In Open Forum Infectious Diseases today, Danish researchers collected data from nonhospitalized adults using a self-administered SARS-CoV-2 antibody test, the Short Form Health Survey (SF-12), and a questionnaire on COVID-related symptoms in fall 2020. A total of 742 COVID-19 survivors and 7,420 uninfected controls were included.
The risk of having at least one long-COVID symptom was 25.0%. Compared with controls, survivors reported poorer general health (OR, 5.9) and were more likely to have a broad range of symptoms, primarily loss of taste (OR, 11.8) and smell (OR, 11.2). Physical and mental health scores were also significantly lower, with differences of -2.5 and -2.0, respectively. Major risk factors for long COVID were female sex and severe initial infection.
"Non-hospitalized SARS-CoV-2 PCR-positive individuals had significantly reduced physical and mental health, and one in four reported persistence of at least one long-COVID symptom," they wrote.
