A new Dutch study has found that as many as one in eight adults exposed to COVID-19 will develop symptoms in the long term.
The study, published in the peer-reviewed journal The Lancet, looked at groups of adults diagnosed with COVID-19 and those who were not infected, and looked at whether they developed new or worsening disease symptoms.
The authors say their study found that about one in eight, or 12.7 percent, of patients in the general population had long-term COVID-19 symptoms.
Judith Rosmalen, professor of psychosomatic medicine at the University of Groningen and lead author of the study, said in a press release released Thursday that including uninfected people in the study gives a more reliable estimate of how long COVID is likely to be present in the general population. .
The Canadian government, citing the World Health Organization, says between 10 and 20 percent of people develop long-term COVID.
The main symptoms of long-term COVID investigated for the Dutch study were chest pain, difficulty or painful breathing, muscle aches, loss of taste and smell, tingling in extremities, lump in throat, feeling hot and cold, heavy arms or legs and general fatigue .
“There is an urgent need for data on the magnitude and scope of the long-term symptoms experienced by some patients after COVID-19 disease,” Rosmalen said in the press release.
“However, most previous research on long-term COVID has not looked at the frequency of these symptoms in people who have not been diagnosed with COVID-19, or at the symptoms of individual patients before the diagnosis of COVID-19.”
The researchers asked participants in the Lifelines COVID-19 cohort study to complete regular digital questionnaires about 23 symptoms commonly associated with long-term COVID.
Lifelines is a multi-generational survey with more than 167,000 participants from the northern population of the Netherlands.
Questionnaires were sent to the same people 24 times between March 2020 and August 2021. The researchers say most of the data was collected before COVID-19 vaccines were rolled out in the Netherlands.
Participants were considered COVID positive if they had a positive test or a doctor’s diagnosis.
The average age of the participants was 53.7, while 60.8 percent were female.
Of the 76,422 participants, 4,231 had COVID-19. This group was then matched with 8,462 uninfected people, taking into account gender, age and when a COVID-19 diagnosis was confirmed in a questionnaire in the positive group.
The study found that 381 of 1,782 COVID-positive participants (21.4 percent) had persistent symptoms, compared with 361 of 4,130 uninfected people (8.7 percent).
Taken together, this means that in 12.7 percent of patients, these symptoms can be attributed to COVID-19, the researchers said.
“The post-COVID-19 condition, also known as lung COVID, is an urgent problem with a rising human toll,” says PhD student and lead author of the study Aranka Ballering.
“Understanding the core symptoms and prevalence of post-COVID-19 in the general population is a major step forward for our ability to design studies that could ultimately lead to successful healthcare responses to the long-term symptoms of COVID-19.”
The authors say the study only involved patients infected with previous COVID-19 variants — not counting Delta and Omicron.
The true prevalence of COVID-19 may also be underestimated because asymptomatic infections go undetected, the researchers said.
The study did not look at other long-term COVID symptoms that have since been identified as potentially relevant, such as brain fog, the researchers said.
Because the study only looked at the Northern Netherlands, the authors say the results may not be generalized to other areas.
Rosmalen says future research should also consider psychological symptoms, such as depression and anxiety, as well as symptoms not included in the study, such as brain fog, insomnia and post-exertional malaise.