It also suggests at least 1 in 10 individuals infected with the SARS-CoV-2 virus that causes COVID-19 will go on to have long COVID symptoms, with the highest percentage of cases in people between 36 and 50 years.
The findings were assembled by a team of US-based researchers, overseen by esteemed American cardiologist Eric Topol, from a review of over 200 peer reviewed studies into long COVID.
They concluded “a significant proportion of individuals with long COVID may have lifelong disabilities if no action is taken”.
Victoria’s Chief Health Officer Professor Brett Sutton described the paper as an “incredibly important analysis on LongCOVID (sic) research.”
Long COVID, they found, is an illness characterised by a range of conditions including neurological effects and impacts to major organs and complex bodily systems.
The pulmonary (heart), respiratory, immune, gastrointestinal, neurological, urinary, endocrine, reproductive systems were all found to be impacted by long COVID.
They also found risk of pulmonary embolism (a blood clot in the lung), cardiac arrest, heart failure, stroke, diabetes and death were increased relative to study control groups.
And among the issues the studies described, the overlapping nature of long COVID with other major multi-system disorders like mast cell activation syndrome (MCAS), chronic fatigue syndrome (CFS), and postural orthostatic tachycardia syndrome (POTS) complicates diagnosis and management.
Little difference between long COVID, CFS, POTS
University of Adelaide researcher Marie-Claire Seely is finalising a year-long study looking at dysautonomia and POTS in long COVID patients. Her findings are consistent with other studies pointing to some post-COVID symptoms as being indistinguishable from better-known disorders.
“In our cohort around 80% of those we saw with long COVID met the criteria on the day we tested them, for POTS… so they all had autonomic dysfunction,” Seely told Cosmos.
The autonomic nervous system is responsible for managing the body’s involuntary process, including blood pressure, heart rate, respiration and digestion.
“When we compared them with healthy controls, they were as disabled as our [non-long COVID] POTS patients,” she says.
“In fact, when we compared them with our POTS patients, we couldn’t tell the difference, so they present virtually identically in terms of their gender makeup.”
That gender makeup is common across several autoimmune disorders triggered by viral infection, including multiple sclerosis: around 80-90% of diagnosed cases are female, and symptoms include fatigue, brain fog, pain, and gastrointestinal problems which are also described by long COVID patients.
“Essentially these are very similar disorders, if not the same,” Seeley says.
Long COVID symptoms from mild cases resolve in a year
While the Nature study warns the dearth of infrastructure to support long COVID diagnosis and management requires governments to fund increasing research and trials into this and other related illnesses, there is suggestion in other new research pointing to quick resolutions for many patients.
Quick – in this case – is relative: within a year according to a study of over one million infectees, published in the BMJ by researchers from the Israeli KI Research Institute.
They found that mild COVID-19 patients have a low risk of post-viral symptoms. Those that do appear to have symptoms resolve within 12 months.
However the Nature study authors express a view that severe cases of long COVID are more likely to experience debilitating effects to key bodily systems, which have indefinite resolution periods.
“We need research that builds on existing knowledge and is inclusive of the patient experience, training and education for the health-care and research workforce, a public communication campaign, and robust policies and funding to support research and care in long COVID,” they say.