A recent study of 340 individuals who had previously been infected with Covid-19 found that nearly one-third of participants experienced some degree of smell loss one year after exposure, while taste loss was not reported. The study, published in JAMA Network Open in April 2024, concluded that taste function was not significantly altered after one year, but olfactory dysfunction persisted in a significant portion of individuals with post-Covid condition, also known as long Covid.
Researchers noted that confusion between taste and smell may contribute to reports of taste loss long after infection, as taste buds only mediate basic oral sensations, while olfaction involves the ability to smell molecules reaching olfactory receptors from the oral cavity. The study also found that more recent SARS-CoV-2 variants, such as Omicron, exhibited less frequent smell loss compared to earlier variants.
A separate study from 2023 published in Rhinology reported that the prevalence of smell loss among individuals infected with the Omicron variant was significantly lower than those infected with the original Covid-19 variant, Alpha variant, and Delta variant.
In the United States, researchers estimate that between 10 million to 35 million adults of working age live with post-Covid condition or long Covid. These individuals may experience a range of new, recurring, or persistent health problems, highlighting the need for effective health policy and support for survivors of Covid-19.
Participants in the study underwent tests to assess their ability to taste flavors and identify different odorants. Results showed that individuals with a history of Covid-19 were more likely to experience some degree of smell loss compared to those without a history of the virus. The researchers noted that individuals with the original and Alpha variant infections were significantly more likely to experience total to severe loss of smell compared to those without a history of Covid-19.
Overall, the study highlights the long-term impact of Covid-19 on olfactory function and the need for further research and support for individuals living with post-Covid conditions.