Olfactory disorder after COVID-19 vaccination

Area of Science:

• Neurology
• Immunology
• Otolaryngology

Background:

• Olfactory dysfunction is a known symptom of COVID-19.
• Post-vaccination adverse events are closely monitored.
• The relationship between COVID-19 vaccination and olfactory disorders requires investigation.

Purpose of the Study:

• To systematically review reported cases of olfactory disorders following COVID-19 vaccination.
• To characterize the clinical presentation, diagnostic findings, and management of these cases.
• To explore potential mechanisms and the need for further research.

Main Methods:

• Systematic review of 16 reported cases.
• Analysis of patient demographics, vaccine types, symptom onset, duration, and severity.
• Diagnostic assessment using Sniffin' Sticks tests and T&T olfactometry.
• Review of treatments and hypothesized pathophysiological mechanisms.

Main Results:

• 16 cases of olfactory disorders (anosmia, parosmia, hyposmia) reported within one week of vaccination.
• Most patients received mRNA (Pfizer, Moderna) or viral vector (AstraZeneca) vaccines.
• Symptoms persisted for weeks to months; diagnoses often indicated mild hyposmia.
• Treatments included vitamins, olfactory training, and corticosteroids; inflammatory response to spike protein is hypothesized.

Conclusions:

• Olfactory disorders can occur post-COVID-19 vaccination, but a direct causal link is not established.
• Clinical evaluation is crucial to differentiate from subclinical COVID-19 infection.
• Further research is necessary to elucidate mechanisms and establish causality.