Long-COVID, chronic fatigue and everything in between - what have we learned and where may it impact on fibromyalgia

ABSTRACT

As the COVID-19 pandemic made its gruesome initial appearance in the first months of 2020, it initially appeared as though nothing could be more distant from this acute, dramatic, life - threatening condition, treated in intensive care units and heroically combated behind personal protective equipment, than fibromyalgia, a chronic pain syndrome treated in clinics by primary care physicians and rheumatologists. Only gradually, as the medical community became more accustomed to the manifestations and complications of COVID-19, did the more chronic aspects of the pandemic come to light with the evolving entity of LONG-COVID syndrome (1). This syndrome was initially treated by a broad spectrum of specialties including infectious disease specialists, pulmonologists, neurologists, with rheumatologists not taking a central role. As more clinical experience was accumulated however, a surprising overlap begins to emerge between LONG-COVID and conditions such as fibromyalgia and chronic fatigue syndrome, an overlap most obvious on a clinical level to rheumatologists well acquainted with the spectrum of fibromyalgia (2). On a clinical level, LONG COVID patients most frequently suffer from fatigue, exercise intolerance, as well as cognitive impairment, all symptoms which overlap with the chronic fatigue syndrome. Sleep disturbances, abdominal complaints, anxiety /depression and myalgia are also not unusual (3). In addition, autonomic dysregulation appears to play a role in LONG COVID (4), as in fibromyalgia. Notably, symptoms typical of fibromyalgia among LONG-COVID patients appear to be particularly common among patients with a previous history of chronic pain, and patients who were actually diagnosed with fibromyalgia before contracting COVID-19 appear to be prone to get worse (5). Notably, an association between fibromyalgia / chronic fatigue and other chronic viral diseases such as EBV/CMV, HIV and viral hepatitis has been well known before the COVID-19 era, so that viral infection has traditionally been considered among the triggers responsible for instigation the syndrome (6). Another aspect of clinical importance regarding the relationship between fibromyalgia and COVID-19 relates to the effect of vaccinations. While vaccinations have previously been speculated to have a causative role in fibromyalgia, mainly based on data relating to the gulf war syndrome, the robustness of this association is not clear. In an era of significant vaccine - hesitancy which often hampers effective attempts at controlling the pandemic, clear data regarding the safety and effectivity of COVID-19 vaccinations regarding fibromyalgia is necessary. Fascinating data has emerged indicating that patients suffering from LONG - COVID may actually have low grade persistent infection, with identification of viral antigens and RNA in tissue as long as one year after initial infection (7). While the general applicability of these findings is not yet clear, they raise the provocative possibility that similar viral vectors might be identifiable in tissues of patients suffering from chronic fatigue or fibromyalgia. Last but not least, the COVID-19 pandemic, including the social distancing measures associated with it, have taken a toll on patients suffering from fibromyalgia even when not personally infected (8). Reduced access to healthcare, lockdown and lack of exercise, anxiety and isolation may all play a role and should be considered by physicians caring for fibromyalgia patients in this era.