A new study seeks to advance the understanding of long COVID.
It finds that long COVID can be divided into three types of conditions, depending on the type of symptoms experienced.
The authors of the study also find links between COVID-19 variants, symptoms, and long COVID’s duration.
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As experts attempt to unravel the tangle of symptoms and long-term effects of what is collectively known as “long COVID,” a new study seeks to provide some clarity.
Working with data collected in a health study app by personalized nutrition company ZOE, researchers from King’s College London in the U.K. have begun to discern some order in the chaos.
The study finds that long COVID can be grouped into three symptom-cluster types: neurological symptoms, respiratory symptoms, and systemic/inflammatory and abdominal symptoms.
Neurological symptoms — the most commonly reported long COVID symptoms — include anosmia/dysosmia, brain fog, headache, delirium, depression, and fatigue. (Loss of taste from COVID is typically attributable to a loss of smell.)
Respiratory symptoms involve possible damage to the lungs and include severe shortness of breath, palpitations, fatigue, and chest pain.
Systemic/inflammatory and abdominal symptoms include musculoskeletal pain, anemia, myalgias, gastrointestinal disorders, malaise, and fatigue.
For the study, researchers analyzed data for 336,652 individuals collected by ZOE’s COVID Symptom Study. Of this group, 1,459 reported post-COVID symptoms defined as more than 12 weeks after acute COVID-19 infection.
Dr. Jai Marathe of Boston University School of Medicine in Massachusetts, who was not involved in the study, told Medical News Today, “This study definitely improves our understanding of post-COVID syndrome and more importantly, who might be at risk of prolonged illness and debility.”
“Physicians and patients,” Dr. Marathe pointed out, “are both looking for answers regarding who is at risk for developing long COVID, how long symptoms will last, what will help resolve the symptoms, etc. While this study does not answer all these questions, it provides a strong framework to build on.”
How variants affect symptoms
The researchers were also able to begin to identify the symptom clusters associated with SARS-CoV-2 variants and with vaccinations.
Dr. Liane S. Canas, corresponding author of the study and postdoctoral research associate at King’s College London, told Medical News Today:
“Our results suggest that chest-related symptoms (respiratory cluster) in the U.K. population were more evident among unvaccinated patients infected by the initial form of the virus [referred to as the “wild” variant].”
“Differently,” Dr. Canas continued, “patients with either the Alpha or Delta variants have shown a higher incidence of neurological symptoms, such as anosmia and brain fog.”
“Unfortunately, we could not robustly evaluate the effect of vaccination for these two variants. For Alpha, we didn’t have enough individuals vaccinated at the time of infection. For Delta, we didn’t have enough unvaccinated individuals at the time of infection who developed long COVID,” she pointed out.
Systemic/inflammatory and abdominal conditions were lightly associated with all variants.
The duration of symptoms
“On average,” said Dr. Canas, “the wild-type form of the virus has shown a longer prevalence of symptoms, 30 weeks when compared with Delta and Alpha at 24 and 25 weeks respectively.”
“However,” she noted, “since we only analyzed data from individuals with illness for longer than 12 weeks, these results are less significant than the profiling of the clusters, and would require further research, which would also consider the effect of vaccination.”
“The findings of the study,” said Dr. Marathe, “suggest that individuals struggling with long COVID, who experience severe shortness of breath, hoarse voice, loss of smell, fatigue, delirium, anosmia, headache, and fever were more likely to [experience] prolonged and severe symptoms.”
“Physicians armed with this information,” she said, “may be able to better counsel their patients and expectations for symptom improvement. They may also work towards targeted treatment approaches that address the symptom cluster impacting, and hopefully improving, clinical care for the patients.”
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