Concerns regarding a suggested long COVID paradigm

We read with great interest the Comment by Chloe Saunders and colleagues1Saunders C Sperling S Bendstrup E A new paradigm is needed to explain long COVID.Lancet Respir Med. 2023; 11: e12-e13Summary Full Text Full Text PDF Scopus (10) Google Scholar that suggested a new paradigm to explain long COVID (also known as post-COVID-19 condition) as an embodied condition with heterogeneous biological, psychological, and social factors that might be interrelated. We value the proposal of transitioning towards an individualised approach for the treatment of patients with post-COVID-19 condition. Due to the multifaceted nature of the condition,2Nalbandian A Sehgal K Gupta A et al.Post-acute COVID-19 syndrome.Nat Med. 2021; 27: 601-615Crossref PubMed Scopus (1733) Google Scholar the universal treatment principle is clearly obsolete in these patients. Incorporating information on experiential, psychological, and social factors in addition to biological findings could be beneficial in providing integral treatment.1Saunders C Sperling S Bendstrup E A new paradigm is needed to explain long COVID.Lancet Respir Med. 2023; 11: e12-e13Summary Full Text Full Text PDF Scopus (10) Google Scholar However, we are afraid the Comment by Saunders and colleagues and the advocated paradigm could be misinterpreted by some readers. The common misconception that post-COVID-19 condition is largely psychological or a consequence of deconditioning is still widely circulating in the general population and even among some professionals. We thus highlight several shortcomings regarding the biological factors in Saunder and colleagues’ main figure and add relevant evidence that could aid the adequate interpretation of their article. Besides those presented in the authors’ main figure, there are indeed important additional factors that have been suggested as contributing to post-COVID-19 condition, including (but not limited to) viral persistence,3Davis HE McCorkell L Vogel JM Topol EJ Long COVID: major findings, mechanisms and recommendations.Nat Rev Microbiol. 2023; 21: 133-146Crossref PubMed Scopus (55) Google Scholar systemic inflammation,3Davis HE McCorkell L Vogel JM Topol EJ Long COVID: major findings, mechanisms and recommendations.Nat Rev Microbiol. 2023; 21: 133-146Crossref PubMed Scopus (55) Google Scholar endothelial dysfunction and vascular damage,3Davis HE McCorkell L Vogel JM Topol EJ Long COVID: major findings, mechanisms and recommendations.Nat Rev Microbiol. 2023; 21: 133-146Crossref PubMed Scopus (55) Google Scholar microclotting,3Davis HE McCorkell L Vogel JM Topol EJ Long COVID: major findings, mechanisms and recommendations.Nat Rev Microbiol. 2023; 21: 133-146Crossref PubMed Scopus (55) Google Scholar mitochondrial dysfunction,4Piotrowicz K Gąsowski J Michel JP Veronese N Post-COVID-19 acute sarcopenia: physiopathology and management.Aging Clin Exp Res. 2021; 33: 2887-2898Crossref PubMed Scopus (76) Google Scholar and altered microbiome.3Davis HE McCorkell L Vogel JM Topol EJ Long COVID: major findings, mechanisms and recommendations.Nat Rev Microbiol. 2023; 21: 133-146Crossref PubMed Scopus (55) Google Scholar These findings have been supported by numerous studies to date; however, these studies must be confirmed through further investigation. All these potential pathophysiological mechanisms should be considered when aiming to explain post-COVID-19 condition in an individual. The authors also present deconditioning as a biological conditioning mechanism for post-COVID-19 condition. Deconditioning is often incorrectly described as the main mechanism of exercise intolerance—a symptom that is frequently present in these patients.5Schwendinger F Knaier R Radtke T Schmidt-Trucksäss A Low cardiorespiratory fitness post-COVID-19: a narrative review.Sports Med. 2023; 53: 51-74Crossref Scopus (4) Google Scholar A review of 32 studies performing cardiopulmonary exercise testing in patients who had had COVID-19 showed that peripheral, followed by cardiovascular, factors and lung diffusion limitations are central to low cardiorespiratory fitness and exercise intolerance.5Schwendinger F Knaier R Radtke T Schmidt-Trucksäss A Low cardiorespiratory fitness post-COVID-19: a narrative review.Sports Med. 2023; 53: 51-74Crossref Scopus (4) Google Scholar Deconditioning should thus be seen as a consequence of persistent organ limitations that prevent the patients from being physically active.5Schwendinger F Knaier R Radtke T Schmidt-Trucksäss A Low cardiorespiratory fitness post-COVID-19: a narrative review.Sports Med. 2023; 53: 51-74Crossref Scopus (4) Google Scholar We hope this correspondence will support the integral model proposed by Saunders and colleagues1Saunders C Sperling S Bendstrup E A new paradigm is needed to explain long COVID.Lancet Respir Med. 2023; 11: e12-e13Summary Full Text Full Text PDF Scopus (10) Google Scholar and contribute to the adequate interpretation of their article. We declare no competing interests. Concerns regarding a suggested long COVID paradigm – Authors' replyWe thank the authors of these three helpful responses to our previously published Comment.1 We welcome Fabian Schwendinger and colleagues highlighting some important factors related to the ongoing immune response that we did not expand upon and for introducing the microbiome. Knowing which factors are necessary and sufficient to understand and treat long COVID (also known as post-COVID-19 condition) across the spectrum is an important goal of a research programme. An exploratory model is needed as the starting point of such a research programme, but scientific models are updated as research progresses. Full-Text PDF A new paradigm is needed to explain long COVIDWe now have adequate data to describe the core symptoms, course, and prevalence of long COVID. Core symptoms include breathing difficulties, muscle pain, anosmia, tingling extremities, and general tiredness. Many of these symptoms are non-specific, but are seen at higher rates in people with long COVID than would be expected in the general population.1 Full-Text PDF Concerns regarding a suggested long COVID paradigmUpon reading Chloe Saunders and colleagues’ Comment,1 it is striking how this new paradigm is essentially the old paradigm for medically unexplained symptoms and contested illnesses.2 The authors advance an alleged philosophical problem they call “taboos based on a dualistic understanding of physical versus mental illness”. They assert such “Poorly integrated explanatory models contribute to poor care and stigma for people who are ill in these specific ways.” Full-Text PDF Concerns regarding a suggested long COVID paradigmIn Chloe Saunders and colleagues’ Comment,1 they recommend a model (which they term new) in which biological, social, experiential, and psychological factors interact to cause long COVID (also known as post-COVID-19 condition). To us—public health scholars with lived experience of post-COVID-19 condition—the model appears indistinguishable from old biopsychosocial models. For decades, such models have been misused to inaccurately characterise similar conditions, such as myalgic encephalomyelitis (also known as chronic fatigue syndrome), as rooted in patients’ own maladaptive psychological processes. Full-Text PDF