Post-Vaccination Chemosensory Dysfunction: Changes Following SARS-CoV-2 Vaccination in a Global Study

To assess post-vaccination changes in chemosensory function among individuals with and without COVID-19-related chemosensory impairment.

In this global, multilingual online survey, participants reported vaccination status, vaccine side effects, and changes in smell and taste before and after each vaccine dose. Responses were collected between May 2022 and August 2023 through convenience sampling. Of 2955 responses, 1352 were included after applying exclusion criteria.

Pfizer-BioNTech accounted for 46.2% of vaccine doses, followed by Sputnik V (16.3%), Moderna (15.4%), AstraZeneca (8.9%), and Sinopharm (7.4%). More than 90% of participants reported no change in general smell or taste following vaccination, regardless of pre-existing chemosensory impairment. Among participants with qualitative chemosensory distortions, improvement was reported by 11%-18% for parosmia, 20%-29% for phantosmia, and 12%-21% for distorted taste, depending on vaccine dose, whereas worsening was reported by 3% or fewer. Side effects varied by vaccine type and were more frequent among individuals reporting worsened chemosensory symptoms.

Most participants reported stable smell and taste perception following vaccination. A subset of individuals with qualitative chemosensory distortions reported improvement, while worsening was uncommon.