I thank Robert Landewe1 for his interest and consent regarding my viewpoint on the resemblance between ‘long COVID’ and fibromyalgia.2 I do agree with him that naming a problem is not sufficient.

However, the question of naming is not secondary. A recent analysis emphasised the fact that post-COVID syndrome prevalence has been largely overestimated because of methodological pitfalls and recommends ‘to create names and diagnostic criteria for specific post-COVID symptoms and syndromes for future study’.3 I was well aware that aligning ‘long COVID’ to fibromyalgia was a rather provocative approach. However, I wanted to highlight the fact that the psychosomatic aspects of post-COVID symptoms were not sufficiently highlighted in previous works. Moreover, Calabrese and Mease proposed a counterpoint of my viewpoint with very good arguments for distinguishing fibromyalgia and ‘long COVID’.4 Like always in science, the debate is stimulating.

More importantly, as said by Robert Landewe, rheumatologists are powerless in the face of fibromyalgia and post-COVID symptoms, which leaves patients often neglected in their conditions. If we accept that fibromyalgia is a final common pathway arising from various forms of or unresolved stress injuries and consider that post-COVID syndrome falls within this classification and is not a result of persistent viral presence or triggered autoimmunity, what measures can be taken to assist patients experiencing symptoms that they may link to a prior SARS-CoV-2 infection?

First, it is important to take the opportunity of the interest of the society to ‘long COVID’ to raise funding to support fundamental and translational research on the mechanisms linking the psyche to the soma, mainly in three directions: immuno-metabolism, neuro-imaging and of course clinical psychology. Interestingly, since my viewpoint was submitted, some articles gave some new information on these elements.

Wong et al found that post-COVID syndrome is characterised by a reduction in plasma serotonin driven by type 1 interferon and that this abnormality can be observed after any viral infection.5 Of note, it has been shown in the large prospective COVIDENCE UK study that the prevalence of post-COVID symptoms was the same after other types of respiratory infections.6 We do know the role of low serotonin in depression, and that fibromyalgia can be observed in the context of depression. It will be of interest to observe whether the selective serotonin reuptake inhibitors antidepressants like fluvoxamine that have been found ineffective in acute COVID,7 can be shown to be protective against post-COVID fibromyalgia-like syndrome.

Another complementary approach would be neuroimaging. With the use of high-power MRI, there is the possibility to follow our thoughts and this technique could help to explain the mechanism of central sensitisation to pain and link hypo or hyper reactivity of some brain areas to changes of metabolites and symptoms.

Finally, clinical psychology is a science that will be supported by advances in the two previous cited domains. Since the submission of my viewpoint, it has been shown in a large Norwegian prospective cohort, that the presence of psychological abnormalities prior to infection was the most important predictor of post-COVID condition (OR=2.12 (1.84 to 2.44)), which supports the fact that post-COVID syndrome is largely favoured by pre-existing psychological factors.8

Thus, further research in immunometabolism, neuroimaging and clinical psychology will tell us if post-COVID syndrome is close to primary fibromyalgia or if it has some specificities.

But now, what can we do for helping our patients with post-COVID condition? On 27 November 2023, there are 442 clinical trials on ‘long COVID’ in clinicalTrials.gov. It is a lot! I do hope that some ideas of drugs will come from fundamental and translational studies mentioned above. Symptomatic drugs against depression or neuropathic pain can already have some utility. Furthermore, if we accept the fact that the psychological aspects of the disease are important, we have to involve psychologists, psychiatrists, pain and rehabilitation specialists for the treatment of these patients. Especially, since these specialists have more experience in helping and guiding their patients to recognise that their symptoms might be linked with a reaction to an event considered as traumatic and not to the persistence of the viral infection or to an abnormal immune reaction.

To conclude, the link between the psyche and the soma is fantastically illustrated by the recent paper from Fraterman et al, showing that pretreatment emotional distress is associated with reduced major response (46% vs 65%) and reduced progression-free survival (74% vs 91%) to neoadjuvant immune checkpoint blockade response in melanoma.9 Thus, yes, before having a better understanding of the mechanisms of the disease allowing for a specific treatment, if we want to help our patients with post-COVID fibromyalgia-like syndrome, we have to take into account their emotional and psychological status.

Not applicable.