Long COVID, the post-infection condition that can encompass a number of symptoms in the weeks following an active COVID-19 infection, is shown to be highly prevalent in a new global analysis of studies published in Open Forum Infectious Diseases.
A second study in The Journal of Infectious Diseases describes the prevalence of long COVID in adolescents in the summer of 2022, and shows that while many teens report lingering symptoms, most are resolved by 3 months post-infection.
In the first study, analysis of 144 studies showed the global pooled long-COVID prevalence through May 2024 was 36% (95% confidence interval [CI], 33% to 40%). Long COVID was persistent when study follow-up was 1 or 2 years, but overall prevalence estimates varied widely across studies, ranging from 3% to 80% in studies published last year.
Among studies from North America, the estimated pooled prevalence was 30% (95% CI, 24% to 38%).
Factors associated with long COVID
In analyzing risk factors, the three strongest for long COVID were being unvaccinated (odds ratio [OR], 2.09; 95% CI, 1.55 to 2.81, meta-analyzed from 7 studies), infections from pre-Omicron variants (OR, 1.74; 95% CI, 1.40 to 2.17, from 6 studies), and female sex (OR, 1.56; 95% CI, 1.32 to 1.84, from 33 studies).
Studies that included only hospitalized patients found higher rates of long COVID than those who had patients with mild cases of the virus.
The two most commonly identified long-COVID symptoms were memory problems and muscle weakness, both with estimated prevalence of 11%.
“We caution that our pooled prevalence estimates represent the percentage of individuals who ever experienced long COVID symptoms during study follow-up, rather than those who are currently experiencing symptoms at a specific point in time, among those with a history of COVID infection,” the authors said. “Therefore, our pooled estimates may overstate the clinical burden of long COVID.”
Lower prevalence in teens at 3 months
US teens surveyed about long COVID in the summer of 2022 describe symptoms at 4 weeks post-infection that improved by 3 months post-infection, according to the second study.
Surveys were given to 784 respondents ages 12 to 17. Of those participants, 264 (34%) said they had tested positive for COVID-19, 291 (37%) never tested positive, and 229 (29%) were never tested for SARS-CoV-2 infection.
At least one symptom lasting 4 weeks or longer were reported by 41% of the positive respondents, compared to 12% of negative respondents and 11% of never-tested respondents. There was no association between COVID variant and odds of reporting lasting symptoms.
“Most symptoms resolved within three months, and less than 30% of adolescents reporting symptoms who tested positive reported their symptoms persisted for three or more months,” the authors concluded.