What is Long Covid?

I first experienced Long Covid in March and April 2020. At that point it was clear that my body hadn’t recovered from the initial infection, but I didn’t know what was happening or why. COVID was still very new, and knowledge was limited. COVID is still a relatively new disease, and researchers are learning more all the time. Happily, there is now a body of evidence that lets us understand more about Long Covid, and what can be done to help manage symptoms. If you are curious to learn more about Long Covid, how it impacts people and the range of symptoms it can cause, read on…

Post-acute sequelae of SARS CoV-2 infection (PACS), also known as Long Covid, is the name given to the range of post viral symptoms experienced by some people infected with SARS-CoV-2 (or COVID). At least 10% of people who have had a COVID infection are impacted by Long Covid, and this number may be up to 40% when more mild cases are taken into account. It is defined as the continuation or development of new symptoms three months after a SARS-CoV-2 infection, with these symptoms lasting for at least two months where symptoms have no other explanation behind them. It can range in level of severity and the strength of symptoms may be consistent over time, or come and go day to day or even hour to hour. 

Long Covid encapsulates over 200 documented symptoms. The most commonly reported include; headache, brain fog, pain, variations in heart rate, extreme fatigue, Post Exertional Malaise (PEM), breathing difficulties, difficulty sleeping, and feelings of anxiety or depression. Symptoms can vary in strength, from people who find they are no longer able to do basic daily tasks, to those who are able to go about their day but have not felt quite right since a COVID infection.

Long Covid symptoms can begin in a few different ways. Some people experience symptoms during an acute infection and find these stay with them for weeks, months or even years. Others seem to recover from an initial infection, but suddenly start to feel symptoms weeks, or even a few months, later. Others may not have the common Long Covid symptoms listed above, but find they suddenly develop a longer term health conditions, or see existing conditions worsen - this can include pre-diabetics developing diabetes, people suddenly developing a heart condition, or existing (or previously undiagnosed) auto immune issues becoming more prevalent. In my case, I experienced both a continuation of initial symptoms after a COVID infection as well as a worsening of a previously mild and undiagnosed autoimmune syndrome. 

The exact driver of Long Covid is not clear, and there may be more than one, including COVID virus (or viral fragments) remaining in parts of the body; tissue damage caused by a COVID infection; or the body mounting an immune response that does not moderate properly. Regardless of the underlying driver, or drivers, evidence has shown that COVID infections are associated with narrowing of the blood vessels (endothelial dysfunction), inflammation in the brain, autoimmune issues and gut microbiome disruption. This leads to a heightened inflammatory response in the body and both an elevated and reduced immune response, with some elements of the immune system over responding while others are less active than expected.

In addition to near term impacts on the body and brain, COVID infections and Long Covid have been shown to increase a person’s risk of developing long term health issues. Evidence also shows that people who have had a COVID infection are at greater risk of experiencing serious cardiac problems, stroke, cancer and developing Alzheimer's, among other long term adverse health outcomes. 

Even for people who have had a COVID infection and feel they are fully recovered, their risk of cumulative damage to their bodies, including organ failure and experiencing Long Covid symptoms, increases with the number COVID infections they have. Evidence of this includes a large-scale study using data from the Veterans Administration in the US. Similarly, COVID infections have been shown to have longer term impacts on the immune system. Researchers believe that part of the impact is to reduce the body’s ability to fight future infections like colds and the flu, and speculate that this is one of the reasons that coughs and colds seem to be lasting longer for many people, and diseases like Respiratory Syncytial Virus (RSV) seem to impact the population more today than they did before the pandemic. 

Knowing the longer-term health implications of Long Covid, and the negative impact symptoms can have on day to day life, has driven us to develop an approach to help reduce the issues people face. While there are no guarantees when it comes to health, our program has been specifically designed for people experiencing Long Covid to do what they can to move the odds in their favor. It focuses on both mitigating the day to day impact symptoms have on their lives, and on reducing the risk of longer-term impacts.   

Links to research that we drew on to inform this post are below.
If you would like more information on how we help people managing symptoms you can find more details on our approach and program page.

Warmly,
Katie

References: 

1. Davis HE, McCorkell L, Vogel JM, Topol EJ. Author Correction: Long COVID: major findings, mechanisms and recommendations. Nat Rev Microbiol. 2023 Jun;21(6):408. doi: 10.1038/s41579-023-00896-0. Erratum for: Nat Rev Microbiol. 2023 Mar;21(3):133-146. PMID: 37069455; PMCID: PMC10408714.
2. Mahdi, A., Zhao, A., Fredengren, E. et al. Dysregulations in hemostasis, metabolism, immune response, and angiogenesis in post-acute COVID-19 syndrome with and without postural orthostatic tachycardia syndrome: a multi-omic profiling study. Sci Rep 13, 20230 (2023). https://doi.org/10.1038/s41598-023-47539-1
3. pre-print SARS-CoV-2 infection triggers pro-atherogenic inflammatory responses in human coronary vessels; Natalia Eberhardt, Maria Gabriela Noval, Ravneet Kaur, Swathy Sajja, Letizia Amadori, Dayasagar Das, Burak Cilhoroz, O’Jay Stewart, Dawn M. Fernandez, Roza Shamailova, Andrea Vasquez Guillen, Sonia Jangra, Michael Schotsaert, Michael Gildea, Jonathan D. Newman, Peter Faries, Thomas Maldonado, Caron Rockman, Amy Rapkiewicz, Kenneth A. Stapleford, Navneet Narula, Kathryn J. Moore, and Chiara Giannarelli, Version 1. bioRxiv. Preprint. 2023 Aug 15. doi: 10.1101/2023.08.14.553245
4. Xu, Sw., Ilyas, I. & Weng, Jp. Endothelial dysfunction in COVID-19: an overview of evidence, biomarkers, mechanisms and potential therapies. Acta Pharmacol Sin 44, 695–709 (2023). https://doi.org/10.1038/s41401-022-00998-0
5. Podrug M, Koren P, Dražić Maras E, Podrug J, Čulić V, Perissiou M, Bruno RM, Mudnić I, Boban M, Jerončić A. Long-Term Adverse Effects of Mild COVID-19 Disease on Arterial Stiffness, and Systemic and Central Hemodynamics: A Pre-Post Study. J Clin Med. 2023 Mar 8;12(6):2123. doi: 10.3390/jcm12062123. PMID: 36983124; PMCID: PMC10055477
6. Neuroinflammation in post-acute sequelae of COVID-19 (PASC) as assessed by [11C]PBR28 PET correlates with vascular disease measures Michael B. VanElzakker, Hannah F. Bues, Ludovica Brusaferri, Minhae Kim, Deena Saadi, Eva-Maria Ratai, Darin D. Dougherty, Marco L. Loggia bioRxiv 2023.10.19.563117; doi: https://doi.org/10.1101/2023.10.19.563117
7. Sharma, C., Bayry, J. High risk of autoimmune diseases after COVID-19. Nat Rev Rheumatol 19, 399–400 (2023). https://doi.org/10.1038/s41584-023-00964-y
8. Li, J., Zhou, Y., Ma, J. et al. The long-term health outcomes, pathophysiological mechanisms and multidisciplinary management of long COVID. Sig Transduct Target Ther 8, 416 (2023). https://doi.org/10.1038/s41392-023-01640-z
9. Memorial Sloan Kettering Library, Covid Impacts: Immune Dysfunction https://libguides.mskcc.org/CovidImpacts/Immune
10. Bowe, B., Xie, Y. & Al-Aly, Z. Acute and postacute sequelae associated with SARS-CoV-2 reinfection. Nat Med 28, 2398–2405 (2022). https://doi.org/10.1038/s41591-022-02051-3
11. Yin, K., Peluso, M.J., Luo, X. et al. Long COVID manifests with T cell dysregulation, inflammation and an uncoordinated adaptive immune response to SARS-CoV-2. Nat Immunol (2024). https://doi.org/10.1038/s41590-023-01724-6