In a study from Weill Cornell Medicine, scientists found the post-COVID syndrome known as long COVID has four major subtypes defined by different clusters of symptoms.
Viral infections sometimes leave patients with a variety of lingering, often nonspecific symptoms.
For SARS-CoV-2, these post-infection syndromes are known popularly as “long COVID,” and more formally as “post-acute SARS-CoV-2 infection” (PASC).
They appear to be very common; estimates of the number of Americans who have had long COVID run as high as 40% of the U.S. adult population.
In the study, the team checked symptom patterns in nearly 35,000 U.S. patients who tested positive for COVID-19 infection and later developed lingering long-COVID-type symptoms.
They detected four major symptom patterns. The first, which accounted for about 34% of patients, was dominated by heart, kidney and circulation-related symptoms.
Patients in this group, compared with those in other groups, were older on average (median age 65), more likely to be male (49%), had a relatively high rate of COVID hospitalization (61%) and had relatively more pre-existing conditions.
This group also had the highest proportion (37%) of patients who were sickened by SARS-CoV-2 during the first big U.S. wave from March to June 2020.
The second symptom pattern, comparable in frequency (33% of patients) to the first, was dominated by respiratory and sleep problems, anxiety, headache and chest pains.
Patients with this pattern were mostly female (63%), with a median age of 51 years and a much lower rate (31%) of COVID hospitalization.
Almost two-thirds of the patients in this group tested positive for SARS-CoV-2 during later waves, from November 2020 to November 2021.
Pre-existing conditions in this cluster centered on respiratory problems such as chronic obstructive pulmonary disorder and asthma.
The other two symptom patterns were dominated, respectively, by musculoskeletal and nervous system symptoms including arthritis (23% of patients), and by a combination of digestive and respiratory symptoms (10%).
To validate their findings, the researchers applied their algorithm to the dataset covering patients from the three southern states, and found very similar results.
The analysis also supported the overall validity of long COVID by showing that, for patients who tested negative for SARS-CoV-2, symptoms appearing in the same 30-to-180-day time interval after the test did not have such clear patterns.
The team says these results should inform ongoing research on the potential mechanisms of long COVID, and potential treatments for it.
For more information about COVID, please see recent studies about new evidence on rare blood clots after COVID-19 vaccination, and results showing very strong brain abnormalities post-COVID.
The study was conducted by Dr. Fei Wang et al and published in Nature Medicine.
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