For some people, contracting COVID means little more than enduring some fatigue and brain fog and it’s all over in a couple of days.
However, for others long COVID drags on and it appears pre-existing conditions are to blame.
It’s estimated that one in three people diagnosed with COVID will suffer from long COVID.
A study by the University of California has found that people with a history of hospitalisations, diabetes and higher body mass index (BMI) are most likely to develop long COVID, while those covered by US public health system Medicaid or who had undergone an organ transplant were less likely to develop the condition.
Surprisingly, the study also found that ethnicity, older age and socioeconomic status were not associated with the syndrome, even though those characteristics have been linked with the risk of severe illness and death from an initial COVID infection.
“This population reveals the startling finding that age, race and economic disadvantage appear unassociated with the development of PASC (post acute sequelae SARS-CoV-2, or long COVID),” the study noted.
“This contrasts with COVID infection rates, hospitalisations and deaths that are disproportionately higher in racial and ethnic minority communities and older people.”
The study attributed the results to the fact that while lower socioeconomic patients had only poor access to healthcare before their diagnosis, they had better access to care following their diagnosis.
“Another possible explanation is that factors that contribute to risks of contracting COVID are not as important in the COVID recovery process and development of PASC,” the study stated.
“Another factor to consider is whether reports of symptoms and expectations for recovery differ across socioeconomic, ethnic and racial groups and whether the tools used to detect PASC equitably capture these reports.”
Of the 1038 patients in the study, the most common symptoms were fatigue, shortness of breath, loss of smell, fever and chills and muscle aches.
Long COVID is defined by the World Health Organization (WHO) as a condition that still exists three months after a positive diagnosis of COVID and cannot be explained by an alternative diagnosis.
The WHO says common symptoms include fatigue, shortness of breath and cognitive dysfunction. Symptoms may be different from the initial diagnosis of COVID or persist from the original illness. Symptoms may also fluctuate or relapse over time.
A study by University of NSW’s Kirby Institute, which specialises in infectious diseases, used data from Sydney’s St Vincent’s Hospital and found elevated levels of types of proteins created by cells in response to the presence of a virus in patients with long COVID.
While these proteins generally disappear after an infection clears, in patients with long COVID they found sustained inflammation detectable for at least eight months following an infection.
St Vincent’s Hospital respiratory therapist Dr David Darley, co-author of the study, told newsGP there were three main hypotheses to explain long COVID.
“The COVID virus could still be lingering in the body … in a reservoir site and patients are still being exposed to COVID antigens,” he said.
“The second is that maybe the virus triggers some sort of autoimmune process that persists.
“Or, patients could have had viral-induced tissue injury or damage, and this is a persistent post-inflammatory response as a result.”
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