One in eight people who contract the coronavirus will develop at least one symptom of long-term Covid, one of the most comprehensive studies of the condition to date presented on Thursday.
With more than half a billion cases of coronavirus recorded worldwide since the start of the pandemic, there is growing concern about the lingering symptoms seen in people with long-term Covid.
But almost none of the existing studies have long compared Covid patients with people who have never been infected, making it possible that some health problems were not caused by the virus.
A new study published in the journal The Lancet asked more than 76,400 adults in the Netherlands to complete an online questionnaire about 23 common long-term Covid symptoms.
Between March 2020 and August 2021, each participant completed the questionnaire 24 times.
During that period, more than 4,200 of them — 5.5 percent — reported contracting Covid.
Of those with Covid, more than 21 percent had at least one new or severely worsened symptom three to five months after becoming infected.
However, nearly nine percent of a control group that did not have Covid reported a similar increase.
This suggested that 12.7 percent of those who had Covid — about one in eight — experienced long-term symptoms, the study said.
The study also recorded symptoms before and after the Covid infection, allowing the researchers to further determine exactly what was involved with the virus.
It was found that common long-term Covid symptoms include chest pain, difficulty breathing, muscle aches, loss of taste and smell and general fatigue.
One of the study’s authors, Aranka Ballering of the Dutch University of Groningen, said Covid has long been “an urgent problem with a rising human toll”.
“By looking at symptoms in an uninfected control group and in individuals both before and after SARS-CoV-2 infection, we were able to explain symptoms that may have resulted from non-infectious health aspects of the pandemic, such as stress caused by disability. and uncertainty,” she said.
The study’s authors said its limitations were that it did not cover later variants, such as Delta or Omicron, and did not collect information about some symptoms such as brain fog, which have since been considered a common sign of long-term Covid.
Another study author, Judith Rosmalen, said that “future research should include psychological symptoms” such as depression and anxiety, as well as aspects such as brain fog, insomnia and a feeling of malaise after even minor exertion.
Christopher Brightling and Rachael Evans, experts from Britain’s Leicester University who were not involved in the study, said it was “a big step forward” from previous long Covid research as it had an uninfected control group.
“It is encouraging that emerging data from other studies” suggest that there is a lower rate of long-term Covid in people vaccinated or infected with the Omicron variant, they said in a linked Lancet comment.
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