Nearly half of COVID-19 survivors may have symptoms of long COVID months after they were first infected, a new study suggests.
Researchers from across Scotland looked at more than 33,000 patients over the age of 16 with a confirmed PCR test for COVID-19 in the past and tracked their symptoms.
Results, published in the journal Nature Communications Wednesday, found that six months later, of the more than 31,000 patients who had had symptomatic COVID, 6% reported not having recovered at all. An additional 42% felt they were only partially recovered.
Patients who reported no recovery were more likely to be women, to have been hospitalized when they had COVID, and to have multiple underlying conditions.
When the team looked at symptoms, they found the most common was tiredness, followed by headache, muscles aches, joint pain and difficulty breathing, respectively.
Patients with an asymptomatic infection were not at increased risk of experiencing symptoms months later.
What's more, having received at least one dose of a COVID-19 vaccine prior to infection reduced the risk of some symptoms including change in taste and/or smell, poor appetite, confusion and difficulty concentrating.
"Our study is important because it adds to our understanding of long-COVID in the general population, not just in those people who need to be admitted to hospital with COVID-19," lead author Jill Pell, a professor of public health at the University of Glasgow, said in a statement.
"By comparing symptoms with those uninfected, we were able to distinguish between health problems that are due to COVID-19 and health problems that would have happened anyway," the statement continued.
Long COVID occurs when patients who have cleared the active infection still have symptoms lasting more than four weeks after recovering. In some cases, these symptoms can persist for months or even years.
Patients can experience a variety of lingering symptoms including fatigue, difficulty breathing, headaches, brain fog, joint and muscle pain, and continued loss of taste and smell, according to the Centers for Disease Control and Prevention.
The authors mentioned some limitations including that most of the participants were white because the study was conducted in Scotland, which has a 96% white population.
"Therefore, it is important that ethnic-specific outcomes are reported by other long-COVID studies with more ethnically diverse populations," the authors wrote.
Additionally, some of the common symptoms were also reported among a control group who had never tested positive for COVID. The symptoms that were most strongly associated with COVID infection were breathlessness, chest pain, palpitations and loss of taste and smell.