John Murphy, The COVID 19 Long-haul Foundation
Abstract Long-haul COVID-19, or post-acute sequelae of SARS-CoV-2 infection (PASC), presents a constellation of persistent symptoms affecting multiple organ systems. Among these, oral and speech-related dysfunctions—including dysgeusia, xerostomia, dentition deterioration, and speech impairment—have emerged as underrecognized yet clinically significant sequelae. This article synthesizes findings from 20 peer-reviewed studies to elucidate the etiological mechanisms underlying these symptoms, focusing on viral persistence, immune dysregulation, neuroinflammation, and epithelial damage. We propose a multifactorial model integrating ACE2 receptor distribution, zinc metabolism, salivary gland pathology, and neurosensory disruption, with implications for clinical management and future research.
1. Introduction
The COVID-19 pandemic has catalyzed unprecedented research into acute and chronic manifestations of SARS-CoV-2 infection. While respiratory and cardiovascular sequelae have dominated clinical discourse, emerging evidence highlights persistent oral and speech-related symptoms in long-haul patients. These include altered taste (dysgeusia), dry mouth (xerostomia), mucosal lesions, dental degradation, and phonatory changes. Understanding the etiology of these symptoms is critical for developing targeted interventions and improving quality of life for affected individuals.
2. Viral Tropism and ACE2 Receptor Distribution
SARS-CoV-2 enters host cells via the angiotensin-converting enzyme 2 (ACE2) receptor, which is abundantly expressed in oral epithelial cells, salivary glands, and taste bud basal cells2. Studies have demonstrated viral RNA persistence in tongue biopsies up to 1.5 years post-infection, suggesting a reservoir for chronic inflammation and epithelial remodeling. This tropism underpins the direct cytopathic effects observed in taste buds and salivary acini.
3. Dysgeusia and Taste Bud Pathophysiology
Taste dysfunction affects up to 45% of COVID-19 survivors, with symptoms persisting for months3. Histological analyses reveal misshapen taste buds with reduced receptor cell density, likely due to impaired regeneration from infected basal cells. Zinc deficiency, induced by systemic inflammation and viral replication, further compromises taste receptor function2. Neuroinflammatory damage to cranial nerves VII, IX, and X may also contribute to altered gustatory signaling.
4. Xerostomia and Salivary Gland Dysfunction
Dry mouth is reported in 2–40% of long-haul patients. Salivary gland ectasia and fibrosis have been documented in imaging and histopathological studies3. The glands’ high ACE2 expression renders them susceptible to viral invasion, leading to reduced saliva production and altered composition. Saliva’s antimicrobial and buffering properties are compromised, increasing susceptibility to oral infections and dental caries.
5. Dentition and Periodontal Impacts
Long-haul COVID-19 has been associated with accelerated dental decay, periodontal inflammation, and tooth loss. These outcomes are multifactorial: reduced salivary flow, altered oral microbiota, nutritional deficiencies, and systemic inflammation all contribute. Case reports describe necrotizing periodontal disease and spontaneous tooth exfoliation in previously healthy individuals. Chronic immune activation may impair gingival healing and exacerbate preexisting conditions.
6. Mucosal Lesions and “COVID Tongue”
Oral mucosal changes—including ulcers, petechiae, and white tongue—have been observed in long-haul patients. These lesions may result from direct viral cytotoxicity, immune-mediated vasculitis, or secondary infections such as oral candidiasis. “COVID tongue,” characterized by tongue swelling and discoloration, reflects epithelial disruption and altered vascular permeability3.
7. Speech Impairment and Neurological Sequelae
Speech dysfunction in long-haul COVID-19 includes dysarthria, phonatory fatigue, and altered resonance. These symptoms may stem from cranial neuropathies, myopathy, or central neuroinflammation affecting motor speech circuits. MRI studies reveal microvascular damage and gliosis in brain regions governing speech production. Additionally, oral dryness and mucosal lesions can mechanically impair articulation.
8. Immunological and Inflammatory Mechanisms
Persistent immune activation is a hallmark of long-haul COVID-19. Elevated cytokines such as IL-6, TNF-α, and IFN-γ contribute to epithelial apoptosis, glandular fibrosis, and neuroinflammation. Autoantibodies targeting epithelial and neuronal antigens have been detected in some patients, suggesting an autoimmune component. These mechanisms may sustain oral and speech-related symptoms beyond viral clearance.
9. Microbiome Disruption and Secondary Infections
SARS-CoV-2 alters the oral microbiome, reducing commensal diversity and promoting pathogenic overgrowth. Dysbiosis may exacerbate mucosal inflammation, impair wound healing, and increase risk of opportunistic infections such as candidiasis and herpes simplex reactivation. Salivary antimicrobial peptides are diminished in long-haul patients, further compromising oral immunity.
10. Clinical Implications and Management Strategies
Recognition of oral and speech-related sequelae is essential for comprehensive post-COVID care. Management may include:
- Zinc supplementation for taste recovery
- Salivary stimulants and hydration strategies for xerostomia
- Antimicrobial mouth rinses and dental hygiene reinforcement
- Speech therapy for phonatory dysfunction
- Immunomodulatory treatments in autoimmune presentations
Multidisciplinary collaboration among dentists, otolaryngologists, neurologists, and immunologists is recommended.
11. Future Directions and Research Gaps
Key areas for future investigation include:
- Longitudinal studies on oral symptom trajectories
- Mechanistic studies on neuroimmune interactions
- Biomarker development for early detection
- Therapeutic trials targeting epithelial regeneration and neurorepair
Understanding the interplay between viral persistence, immune dysregulation, and tissue remodeling will be critical for advancing care.
12. Conclusion
Long-haul COVID-19 exerts profound effects on oral health, taste, saliva production, dentition, and speech. These symptoms arise from a complex interplay of viral, immunological, and neurological mechanisms. Clinicians must remain vigilant for these sequelae, and researchers must continue to unravel their etiologies to inform targeted interventions. Oral and speech-related dysfunctions are not peripheral concerns—they are central to patient well-being and deserve focused attention in the evolving landscape of post-COVID care.