A new study from the American College of Physicians finds that many people report “long-COVID” after recovery from acute cases, and that the causes of these persistent symptoms are still unclear – even after comprehensive patient evaluations.
Researchers from the US National Institutes of Health (NIH) found that 55% of patients previously infected with mild or moderate COVID experienced persistent symptoms.
The cohort study, published in Annals of Internal Medicine, studied 189 patients who were at least six weeks out from laboratory documented COVID and 120 control patients to characterize medical sequelae and persistent symptoms after recovery.
The most common persistent symptoms noted in this study were fatigue, laboured breathing, chest discomfort, parosmia, headache, insomnia, memory impairment, anxiety, and concentration impairment after infection.
According to the authors, in the absence of objective abnormalities on diagnostic evaluation, the subjective symptoms resemble illnesses such as chronic fatigue syndrome, other post-infection syndromes, and mental health disorders such as depression and anxiety.
The authors also report that they did not find evidence of persistent viral infection or damage to tissue and organs in patients with persistent symptoms.
However, those patients self-reported worsened physical and mental health and lower quality of life than either control participants, or patients with COVID but without persistent symptoms.
Despite the causes remaining unknown, a US study, published in Nature Medicine on 26th May, revealed that people who get COVID after being vaccinated can still experience symptoms associated with long-COVID six months after diagnosis.
The research, led by Ziyad Al-Aly from the Washington University School of Medicine, investigated the long- and short-term risks associated with breakthrough infection (BTI) in some 34,000 vaccinated people versus several control groups, using national healthcare data from the US Department of Veteran Affairs.
They also found that the risks of long-Covid (and death) are higher for unvaccinated people six months after infection, compared to those who got jabbed.
Compared with unvaccinated people who had been infected, during the first 30 days after diagnosis of BTI there were 10.99 fewer deaths per 1,000 people and 43.38 fewer people per 1,000 who experienced at least one symptom.
However, compared to those who had never recorded a positive test for COVID, vaccinated people who got a breakthrough infection had a 1.75 times higher risk of death six months after getting sick – and a 1.5 times higher risk of symptoms linked to long-COVID.
In separate analyses, vaccinated people who were hospitalized with BTI had a higher estimated risk of death (43.58 more deaths per 1,000) and of developing symptoms of long-COVID in the first 30 days after diagnosis, than that of people who were hospitalized with seasonal influenza.
Mr Al-Aly and colleagues conclude that these results could be used to help enhance strategies aimed at both preventing BTI and optimising care for those who are affected.