With successful vaccines helping prevent hospitalizations and deaths from COVID-19 scientists are racing to understand the long-term effects of this novel disease. Dubbed "long COVID", a handful of new studies are beginning to shed light on this unusual chronic condition, highlight who is more susceptible and what kind of symptoms are most common.
A new study led by researchers at University College London is presenting the largest investigation into the symptoms of long COVID conducted to date. The research surveyed nearly 4,000 long COVID subjects spanning 56 countries.
“While there has been a lot of public discussion around long COVID, there are few systematic studies investigating this population; hence relatively little is known about its range of symptoms, and their progression over time, the severity, and expected clinical course (longevity), its impact on daily functioning, and expected return to baseline health,” says senior author Athena Akrami.
The research focused on those initial COVID-19 cases, diagnosed early in 2020. All participants were over the age of 18 and suffered from symptoms lasting at least 28 days.
A striking 203 different symptoms were identified in the study, the most common matching prior long COVID studies – fatigue, brain fog and reductions in exercise capacity. But a huge array of diverse symptoms were also reported, including sexual dysfunction, shingles and bladder issues.
“Headaches, insomnia, vertigo, neuralgia, neuropsychiatric changes, tremors, sensitivity to noise and light, hallucinations (olfactory and other), tinnitus, and other sensorimotor symptoms were also all common, and may point to larger neurological issues involving both the central and peripheral nervous system,” notes Akrami.
Only 6.8 percent of the entire cohort had completely recovered and were symptom-free by the time the study was completed. The vast majority of long COVID patients surveyed (89.1 percent) reported exercise or stress as the primary trigger for symptom relapses, and almost half of the cohort were working less than they were pre-illness.
Although this new study offers a comprehensive insight into the characteristics of long COVID, it doesn’t investigate how common the condition is. However, its prevalence seems to be closely connected to the severity of the first few weeks of infection.
University of Birmingham researchers have suggested those COVID-19 patients suffering from five or more symptoms in their first week of infection are the cohort most likely to suffer from long COVID. This finding is irrespective of age or gender.
An early long COVID study looking at more than 1,700 hospitalized subjects from Wuhan found 76 percent of that cohort reported at least one ongoing symptom six months later. More recent research is backing up those early findings, affirming around 70 percent of COVID-19 cases severe enough to need hospitalization result in some kind of persistent symptoms up to six months after the acute illness.
For those suffering more mild disease the research so far suggests between 10 and 30 percent will experience some kind of lingering symptoms. One calculation from researchers at Imperial College London estimates there currently could be more than two million people in England suffering from long COVID symptoms.
Danny Altmann, from Imperial College London, is part of the front line of long COVID research. He says one of the only things that is clear right now is that long COVID is certainly a real phenomenon.
“… I’m very impressed when I look around the world, at different cohorts of people in different countries who've been infected, that they're all describing the same kind of thing,” says Altmann. “They're saying that they may have had quite mild COVID-19 infection, or severe infection, or even asymptomatic infection, and yet for several weeks, or months, or now years afterwards, many of them are describing the same kind of pattern of symptoms.”
Beyond that, however, is a huge array of questions that will take time to answer. Is long COVID a passing condition that will dissipate after a year or two? Does long COVID predispose a person to other illnesses? What exactly is causing long COVID, and how can we treat it?
Altmann says it is precisely this “uncharted territory” we are entering that is so worrying. There is precedent for viral infections triggering long-term health issues – glandular fever, Epstein Barr virus and Ebola are just a few examples of long-term immune disruptions following an acute infection.
“And without straying into politics, it's one of the reasons why I do worry,” says Altmann, “when I see people being laissez faire, saying ‘Well, if we've got the stage where people aren't dying, and aren't filling up the intensive care units, do we need to care?’. And the answer is, I think, until we've got more data, we don't know how much we need to care.”
