Anosmia or Ageusia Following COVID-19 Vaccination: A Systematic Review

Aim: To systematically review the cases of anosmia or ageusia after receiving the coronavirus disease 2019 (COVID-19) vaccine. Methods: A systematic search was conducted in electronic databases, including Web of Science, Scopus, Embase, and PubMed, to identify any published study that evaluated the anosmia or ageusia after receiving the COVID-19 vaccine, including case reports, case series, letter to editor articles with reported cases regarding our topic, or observational studies with at least 1 eligible patient consisted with our criteria. We excluded the studies that reported anosmia or ageusia due to COVID-19 infection and non-COVID-19 vaccines. Results: Five studies consisting of 11 patients were included in this systematic review. Of the 11 patients, 5 patients had received the Pfizer COVID-19 vaccine and 6 patients received the Oxford-AstraZeneca COVID-19 vaccine, of which 6 patients developed symptoms after the first dose of vaccination and 5 patients were symptomatic after the second vaccine dose. Most of the patients developed symptoms within 1 week after the vaccination. The disorders of the patients included partial or total anosmia, parosmia, phantosmia, hyposmia, ageusia, and dysgeusia. Also, the patients had symptoms other than smell or taste disorders, including arthralgia, fever, chills, rhinorrhea, myalgia, abdominal pain, fatigue, muscle weakness, altered bowel pattern, aural fullness, tinnitus, and headache. Most of the evaluated patients did not receive any treatment as for their disorders. However, in some cases, treatment with oral corticosteroids or dietary supplementation was required. Conclusion: Anosmia and ageusia are important symptoms of COVID-19 vaccination. These symptoms will resolve without any treatment in most cases, although some interventions may be needed in some patients.