Long COVID Symptoms in 6% of People with Symptomatic Infection

Three months after symptomatic COVID-19 infection, 6.2% of patients had persistent cognitive or respiratory problems or fatigue in 2020 and 2021, a new study found.

The study, published in JAMA, included data from 54 studies and two medical record databases on 1.2 million individuals from 22 countries with symptomatic SARS-CoV-2 infections. Investigators with the Global Burden of Disease Long COVID Collaborators group analyzed the proportion of symptomatic COVID-19 patients who had at least one of three clusters of long COVID symptoms three months after infection.

“Importantly, we have anchored our estimates on the difference between those having experienced a SARS-CoV-2 infection and those not; or by comparing people rating symptoms before and after they had COVID-19,” Theo Vos, PhD, of the Institute for Health Metrics and Evaluation at the University of Washington, told Contagion. “As all these symptoms are common, not correcting would lead to overestimation.”

After adjusting for health status before infection, they found that 6.2% of patients had persistent symptoms, including 3.7% with respiratory problems, 3.2% with persistent fatigue, pain or mood swings, and 2.2% with cognitive problems three months after infection.

“Long COVID is fairly common among those with symptomatic COVID-19; twice more common in women than men and children at half the risk of adult males (and thus a quarter of risk in adult women),” Vos said.

Severe infection, particularly hospitalization in the ICU, was associated with a greater risk for long COVID and for a longer duration of symptoms.

“Multiplying these risks with the large numbers of infections in the world means that in 2020 and 2021 close to 150 million people were affected by these common symptom clusters of long COVID,” Vos said.

The study likely undercounted the proportion of people affected by prolonged symptoms because it didn’t cover the full spectrum of symptoms and missed people with less severe symptoms that didn’t interfere with normal activities, he said.

Women were more likely than men to experience at least one of the three long COVID clusters, which affected 10.6% of women age 20 and older and 5.4% of men age 20 and older. Only 2.8% of patients younger than 20 were affected.

The average duration of symptoms was nine months. Among those experiencing symptoms three months after infection, 15.1% continued to experience symptoms a year after infection.

“While we estimate that majority of cases recover within a year, it still leaves many persons with ongoing symptoms,” Vos said. “Information is not yet there to determine the course of their symptoms beyond 1 year.”

The investigators will update the findings, taking into account research suggesting that the Omicron variant of SARS-CoV-2 was less likelyto lead to long COVID and that vaccination and prior infection provided some protection.

“Countries should prepare to appropriately provide recognition and care for people with long COVID symptoms and (in due time) support those on the path to recovery with support to return to work/school,” Vos said.