Background: As of April 10th, 2021, \>1 million Canadians have contracted Coronavirus-2019-disease (COVID-19), with 398,835 infected in Ontario of whom 92% are deemed "recovered" by public health. Despite the recovery, a considerable section (10-15%) of COVID-19 survivors, irrespective of their severity (hospitalized or mild), continue to have symptoms or develop new ones. These vary in type and severity between individuals, ranging chronic fatigue, anosmia, dyspnea, diffuse pain, anxiety, cognitive impairment that is not attributed to any clinical diagnosis. This is now termed the Post-Acute COVID-19 Syndrome (PACS) or long-COVID. Much remains unknown as to what underlies this constellation of symptoms and what more severe pathologies it can lead to.
Rationale to study autoimmunity in PACS: First, diverse circulating auto antibodies and lymphopenia are associated with COVID-19 severity. Second, though the male: female sex ratio for contracting the infection and recovery rate is comparable, recent studies indicate PACS to be more prevalent in females, with increasing age and BMI. Taken together these are hallmark etiological factors and demographics underlying diverse autoimmune pathologies. Third, the lung being the primary affected organ may be the site of chronic auto inflammation itself. There is evidence of auto reactivity and detectable autoantibodies in sputa associated with autoimmune diseases with pulmonary complications (such as rheumatoid arthritis, vasculitis). Finally, there is a growing body of anecdotal evidence highlighting autoimmune diagnoses post-COVID, ranging from Guillain Barre to vasculitis to lupus, in otherwise previously healthy individuals. Our preliminary data suggests 35% of individuals post-COVID have \>2 circulating autoantibodies at a high disease-modifying titre, significantly associated with health outcomes. While viruses, in general, have the innate capacity to induce autoimmunity (may not be specific to SARS-CoV2), the magnitude of PACS individuals affected warrants further investigation.
