ABSTRACT
Long COVID is characterized by the emergence of multiple debilitating symptoms following SARS-CoV-2 infection. Its etiology is unclear and it often follows a mild acute illness. Anecdotal reports of gradual clinical responses to histamine receptor antagonists (HRAs) suggest a histamine-dependent mechanism that is distinct from anaphylaxis, possibly mediated by T cells, which are also regulated by histamine. T cell perturbations have been previously reported in post-viral syndromes, but the T cell landscape in patients who have recovered from mild COVID-19 and its relationship to both long COVID symptoms and any symptomatic response to HRA remain underexplored. We addressed these questions in an observational study of 65 individuals who had recovered from mild COVID-19. Participants were surveyed between 87 and 408 days after the onset of acute symptoms; none had required hospitalization, 16 had recovered uneventfully, and 49 had developed long COVID. Symptoms were quantified using a structured questionnaire and T cell subsets enumerated in a standard diagnostic assay. Patients with long-COVID had reduced CD4+ and CD8+ effector memory (EM) cell numbers and increased PD-1 (programmed cell death protein 1) expression on central memory (CM) cells, whereas the asymptomatic participants had reduced CD8+ EM cells only and increased CD28 expression on CM cells. 72% of patients with long COVID who received HRA reported clinical improvement, although T cell profiling did not clearly distinguish those who responded to HRA. This study demonstrates that T cell perturbations persist for several months after mild COVID-19 and are associated with long COVID symptoms.
Subject(s)
COVID-19/complications , COVID-19/immunology , Histamine Antagonists/therapeutic use , T-Lymphocytes , Adult , Aged , COVID-19/diagnosis , Female , Histamine , Humans , Male , Middle Aged , SARS-CoV-2/immunology , T-Lymphocyte Subsets/immunology , Young Adult , Post-Acute COVID-19 SyndromeABSTRACT
Viral infections and their emergence continue to pose a threat to human lives. Up to the present, there are limited numbers of vaccines that effectively work and few antivirals licensed for use in clinical practice. Added to this is the increase in antiviral resistance, meaning that drugs that do work are at risk of reduced efficacy. The recent global pandemic of coronavirus 2019 has provided evidence for the risk of a preventative vaccination and effective treatment of viruses' subsequent consequences. The aim of this article is to review traditional and herbal treatments for infections, specifically addressing gastrointestinal and respiratory viral infections.