[Contains a number of mentions of ME/CFS] Introduction Significant time has passed since the coronavirus disease of 2019 (COVID-19) pandemic outbreak, which led to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection in hundreds of millions of individuals all around the globe. Accumulation evidence along the pandemic raised an association between the SARS-CoV-2 and autoimmunity (1). SARS-CoV-2 infected patients have a high presence of various autoantibodies (1). Moreover, numerous cases of new-onset of autoimmune-related disorders had been documented following the infection, including both organ-specific and systemic autoimmune diseases (1). Recent studies focused on analyzing recovered COVID-19 patients demonstrate a broad spectrum of persistent and systemic symptoms, which had got the novel terms of “post-COVID syndrome”, “long COVID” and “chronic COVID-19” (2). This new disorder had led to the understanding that the absence of SARS-CoV-2 following COVID-19 does not necessarily mean full recovery (2). Studies conducted follow-ups on COVID-19 patients indicate that 50-80% of symptomatic COVID-19 patients who recovered report non-specific symptoms, most commonly fatigue, headache, dyspnea, anosmia, and memory complaint (3–5). An Italian study that examined patients after a mean of 60 days from the first COVID-19 symptom on-set had found only 12.6% of the patients completely recovered; 55% had three or more symptoms, and worsened quality of life was observed among 44% of patients (3). Intriguingly, a systematic review and meta-analysis reported more than 50 possible long-term effects of the SAR-CoV-2 infection (6). The chronic phase of COVID-19 is also presented in objective findings; for example, a study conducted in Germany had found that 78% of recently recovered symptomatic COVID-19 patients had at least one chronic symptom; the most common abnormality was myocardial inflammation (60%) (4). In this issue of the journal, Bertin D et al. documented a case of post-COVID syndrome with a one-year follow-up. This case describes persistent anti-cardiolipin IgG autoantibodies and eosinopenia with ongoing neurologic symptoms, demonstrating the long-term disease course of COVID-19 in many patients. Anti-cardiolipin autoantibodies and eosinopenia were defined as independent factors associated with COVID-19 severity, indicating their active involvement in the progression of the disease (7,8). Additional studies that included follow-up on recovered COVID-19 patients describe similar findings: patients report respiratory, neurologic, and non-specific symptoms, accompanied by the presents of autoantibodies (6). Interestingly, in a one-year prospective cohort study, neurocognitive symptoms frequency were found significantly higher in patients with ANA titer of ≥1:160 in comparison to <1:160 at 12 months post–COVID-19 symptom onset (9). It should be emphasized that the development of autoantibodies, which appears to be common following symptomatic SARS-CoV-2 infection, could act as the preclinical stage of many autoimmune diseases. Thus, the long-term autoimmune implications of SARS-CoV-2 could be severe. Open access, https://www.ijidonline.com/article/S1201-9712(21)00867-5/fulltext
