No Longer a Confirming Indicator, Loss of Smell or Taste no Longer Signifies COVID

Once a hallmark sign of many COVID-19 cases, the sudden loss of smell and taste has become less common, with only a small fraction of new patients reporting it last year. This finding comes from analysis of a sweeping dataset of medical records gathered by the National Institutes of Health. Previously, people associated loss of smell with the potential of having COVID-19, but now it’s harder to tell, according to Dr. Evan Reiter, medical director of VCU Health’s Smell and Taste Disorders Center.

Dr. Reiter led a study published in the journal Otolaryngology-Head and Neck Surgery, which examined the odds of patients with COVID-19 also reporting loss of smell and taste. The study found that while chemosensory loss occurred in about 50% of cases early in the pandemic, it is now only prevalent in about 3% to 4% of cases in more recent waves, such as the Omicron variant.

This research is among the latest to demonstrate how COVID-19 symptoms have changed with the emergence of new variants and the development of immunity from infections and vaccinations. A study from University College London also reported a significant decrease in the proportion of cases reporting loss of taste or smell after the emergence of the Omicron strain in 2021.

A potential for new treatments?

Scientists are now gaining more clues as to why many patients have not recovered their sense of smell or taste after COVID-19 infections. Research conducted by a team led by Duke University and Harvard University revealed that an immune response targeting nerve cells in the nose may persist long after the virus has dissipated. The researchers analyzed samples from patients with ongoing smell loss and found evidence of inflammation driven by T cells, suggesting ongoing damage or prevention of repair.

These findings could lead to new treatments that directly curb the immune response and promote nerve cell regeneration or recovery. The National Institutes of Health has recently started enrolling volunteers in trials for treatments of long COVID symptoms, although no specific treatments for smell loss have been announced.

Smell training and nose injections

Currently, doctors have limited options to treat patients with loss of smell. Olfactory training, which involves exposing the damaged smell nerves to pleasant smells, is a common starting point. Steroids have also been tried, but evidence of their effectiveness is scarce. A promising approach involves using concentrated formulations of platelets from the patient’s own blood to regrow tissue in the nose. However, treatments carry risks, and many patients recover their sense of smell without intervention.

Overall, the research on loss of smell in COVID-19 patients provides valuable insights into the changing nature of the virus and its symptoms. Understanding these changes can guide the development of better treatments and improve patient outcomes.