Is SARS-CoV-2 (COVID-19) postviral olfactory dysfunction (PVOD) different from other PVOD?

Abstract

Background: The SARS-CoV-2 virus continues to spread rapidly across the globe afflicting many with Coronavirus Disease 2019 (COVID-19). As the infection rates rise, a growing number of SARS-CoV-2 positive individuals have been reported to complain of olfactory disturbances at an alarming rate. Postviral olfactory dysfunction (PVOD) is a well-known phenomenon that may explain the olfactory dysfunction reported by SARS-CoV-2 infected individuals.

Methods: A scoping literature review was performed to identify studies that investigated the mechanisms of postviral olfactory dysfunction. Studies demonstrating pathophysiological, histological, immunochemical, and epidemiological outcomes of PVOD were included.

Results: Fourteen studies were included in addition to one international news article. Three studies reported destruction of the olfactory epithelium following intranasal inoculation of various viral strains in mice. Three studies isolated pathogenic, anosmia inciting viruses (Parainfluenza virus, Human Coronavirus, Rhinovirus) through nucleic acid amplification. Eleven studies demonstrated female predilection in patients with PVOD and COVID-19 associated olfactory dysfunction, of which the majority were over 50 years old.

Conclusions: PVOD and COVID-19 associated olfactory dysfunction demonstrates considerable similarities in epidemiological trends and disease sequela of other viruses to suggest identical pathophysiological mechanisms. Further studies such as intranasal inoculation and histological biopsies are needed to support our hypothesis.

Keywords: Olfaction; Olfactory disorders; Postviral olfactory dysfunction; SARS-CoV-2 (COVID-19); UPSIT.