The long COVID syndrome: A conundrum for the allergist/immunologist

Abstract

Background: The long coronavirus disease 2019 (COVID-19) syndrome includes a group of patients who, after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibit lingering mild-to-moderate symptoms and develop medical complications that can have lasting health problems. Objective: The purpose of this report was to examine the current body of evidence that deals with the relationship of COVID-19 infection with the long COVID syndrome to define the possible immunologic mechanisms involved in the pathogenesis of long COVID and to describe potential strategies for the diagnosis and clinical management of the condition. Methods: Extensive research was conducted in medical literature data bases by applying terms such as long COVID, post-COVID-19 condition, pathogenesis of long COVID, management of the long COVID syndrome. Results: The post-COVID conditions, a more recent and less anxiety-inducing term for the patient than long COVID or "long haul," is an umbrella term for a wide range of physical and mental health symptoms similar to those seen in patients with the myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), experienced by some patients and are present ≥ 4 weeks after SARS-CoV-2 infection. Although the precise reason why long COVID develops is unknown, one of the major causes is thought to be related to chronic inflammation with overproduction of inflammatory cytokines responsible for the symptoms of the disorder. Conclusion: Long COVID is a growing burden for millions of patients, health-care providers, and global health-care systems, and is a particular challenge for the allergist/immunologist. Many survivors of COVID-19 struggle with multiple symptoms, increased disability, reduced function, and poor quality of life. The allergist/immunologist can assist the total health-care team's efforts in providing a comprehensive and coordinated approach to the management of these patients by promoting comprehensive vaccination and rehabilitation and social services that focus on improving physical, mental, and social well-being, and by establishing partnerships with specialists and other health-care professionals who can provide behavioral, lifestyle, and integrative approaches that may have much to offer in helping patients cope with their symptoms.

Figure 1.

Schematic representation of some of the functionally active autoantibodies linked to COVID-19. In the center is shown the SARS-CoV-2; around it, at the upper part of the figure, are the autoantibodies; at the bottom part of the figure appear some of the chronic symptoms associated with COVID-19. COVID-19 = Coronavirus disease 2019; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2. Reproduced with permission from Ref. .

Figure 2.

Schematic representation of the common clinical manifestations observed in long COVID-19. COVID-19 = Coronavirus disease 2019. Reproduced with permission from Ref. .

Figure 3.

Three groups of serum total and IgG SARS-CoV-2 spike antibody responses were observed by SARS-CoV-2: (1) low, (2) intermediate, and (3) high. The cutoff points for the low group total ab level ranged from 0 to 600 μg/mL and, for the IgG level, from 0 to 5μg/mL; the cutoff points for the intermediate group total ab level ranged from 601 to 2000 μg/mL and for the IgG from 5 to 17 μg/mL; the cutoff points for the high group total ab level ranged from 2001 to >2500 μg/mL and, for the IgG level, from 17.1 to >20 μg/mL. IgG = Immunoglobulin G; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2; ab = antibody. Reproduced with permission from Ref. .