madeleineshort

What is the science on long-COVID?

Question:  I am interested in so-called “long-term covid.”   How clear is the science on the symptoms of long-term covid?  Is there a firm grasp on the range of impacts the virus can have, long term?  I have heard COVID can trigger more serious disorders such as diabetes and other illnesses caused by organ problems.

Answer: As it so happens, Nature published a really informative overview of long-COVID just a few days ago, The four most urgent questions about long COVID.  I drew from that up-to-date overview and a few other sources to pull together this synthesis.  We are learning so much and have so much to learn.  What we do know includes: a) a substantial proportion of individuals suffer from long-COVID; b) the symptoms vary person-to-person and can involve physical, cognitive, and mental health impairments; and c) COVID infection can result in other long-term consequences, including type 1 diabetes.

  1. How do we define “long-COVID”?: There is no widely agreed upon definition of “long-COVID,” but several groups, including the UK’s Office of Statistics have defined it as COVID-19 symptoms that last more than 4 weeks.  “Long-COVID” is an umbrella term that likely captures a constellation of health challenges/syndromes that require further categorization once more is known.
  2. How common is long-COVID?: A study by the UK’s Office of Statistics following 20,000 individuals who tested positive for COVID-19 found that “…13.7% continued to experience symptoms for at least 12 weeks. This was eight times higher than in a control group of participants who are unlikely to have had COVID-19, suggesting that the prevalence of ongoing symptoms following coronavirus infection is higher than in the general population.” (Figure 1) Among participants, a higher proportion of women (14.7%) than men (12.7%) were self-reporting symptoms for 12 weeks or longer. 
  3. What are common long-COVID symptoms?: A social media survey led by a research team at University College London who collected data from >3,700 participants in 56 countries found that “The most likely early symptoms were fatigue, dry cough, shortness of breath, headaches, muscle aches, chest tightness, and sore throat. The most frequent symptoms reported after month 6 were fatigue, post-exertional malaise, and cognitive dysfunction.”  The science here is still evolving.
  4. What are the long-term consequences?: Symptoms are varied and can involve physical, cognitive, and mental health impairments.  
  5. What causes long-COVID?: We still don’t know.  Hypotheses include: a) inactivated viral particles that have not cleared the body cause disruption in the body, leading to ongoing immune response and ongoing symptoms; b) COVID causes the immune system to overreact, and prompts auto-immue disorder(s).  Interestingly, as described in Nature, a recent study found “little relationship between the severity of the acute phase or the levels of organ damage, and the severity of long COVID.”
  6. What about diabetes?: Yes, evidence is accumulating that SARS-CoV-2 can damage the pancreas, and can cause type 1 diabetes.  Two studies published last month in Cell Metabolism highlight the relationship and this overview published 4 days ago by National Geographic provides an easy to read narrative of the evidence and biologic mechanisms.       

Figure 1. Persistence of COVID symptoms over time (from Nature)