Worldwide, 49% of COVID-19 survivors reported persistent symptoms 4 months after diagnosis, estimates a meta-analysis of 31 studies published late last week in The Journal of Infectious Diseases.
University of Michigan researchers, who conducted a systematic review on Jul 5, 2021, also found the prevalence of long COVID at 1 month at 37%, while it was 25% at 2 months and 32% at 3 months. Fifty studies were identified in the review, and 41 were included in a quantitative synthesis, and 31 reporting overall prevalence were meta-analyzed.
The 50 studies included a total of 1,680,003 COVID-19 patients, including those who were hospitalized (67,161 patients from 22 studies), nonhospitalized (4,165 from 5 studies), and any COVID-19 patients, regardless of hospitalization status (1,608,677 from 23 studies).
Impact on health, workforce 'enormous'
Estimated global prevalence of long COVID was 43% (95% confidence interval [CI], 39% to 46%), although estimates ranged from 9% to 81%, which the study authors said may be attributable to differences in sex, region, study population, and follow-up.
Long COVID prevalence among hospitalized patients was 54% (95% CI, 44% to 63%), while it was 34% (95% CI, 25% to 46%) for outpatients.
Regionally, estimated pooled prevalence of lingering COVID-19 symptoms was 51% (95% CI, 37% to 65%) in Asia, 44% (95% CI, 32% to 56%) in Europe, 31% (95% CI, 21% to 43%) in North America, and 31% (95% CI, 22% to 43%) in the United States.
Worldwide, estimated prevalence of long COVID was 37% (95% CI, 26% to 49%) 1 month after diagnosis, 25% (95% CI, 15% to 38%) at 2 months, 32% (95% CI, 14% to 57%) at 3 months, and 49% (95% CI, 40% to 59%) at 4 months. The most common symptoms were fatigue (23%), followed by memory problems (14%), shortness of breath (13%), sleep problems (11%), and joint pain (10%).
Overall, the meta-analysis showed that a higher percentage of women reported long COVID symptoms than men (49% vs 37%, respectively) and that preexisting asthma was a predisposing factor for lingering symptoms. Risk factors identified in the studies that weren't meta-analyzed included severe initial illness, older age, and underlying conditions such as obesity and hypothyroidism.
Findings from the study show that the prevalence of long COVID is substantial, the health effects of infection seem to be prolonged, and the condition could stress the healthcare system, the researchers said.
"We recommend continued attention be focused on identifying patients at-risk of developing post COVID-19 condition and on quantifying duration of symptoms. With an estimated 200 million individuals affected, post COVID-19 condition's impact on population health and the labor force is enormous," they concluded.
"It is imperative that those affected are provided proper health, social, and economic protections."
