Nikhil Prasad Fact checked by:Thailand Medical News Team Jul 29, 2025 1 month, 2 weeks, 19 hours, 42 minutes ago
Medical News: New Animal Study Reveals Omicron Can Cause Hidden Smell Problems
A new study has revealed that the Omicron variant of SARS-CoV-2, though often thought to spare the nose, still causes significant smell issues—even if people don’t notice them immediately. Researchers from several leading institutions in France and the United States investigated how Omicron affects the sense of smell using a Syrian hamster model, known to mimic human responses.
Omicron Still Disrupts Sense of Smell but in Subtle Ways
The research was conducted by scientists from UMR 1161 Virologie, INRAE-ENVA-ANSES, École Nationale Vétérinaire d'Alfort in Paris, France; Unité de Virologie et Immunologie Moléculaires (UR892), INRAE, Université Paris-Saclay, Jouy-en-Josas, France; the Viral Genetics and Biosecurity Unit (GVB), French Agency for Food, Environmental and Occupational Health Safety (ANSES), Ploufragan, France; and the Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, USA.
While most people infected with Omicron don’t report loss of smell like in earlier waves of the pandemic, this
Medical News report uncovers that many may still experience milder forms of smell dysfunction without even realizing it. This includes reduced sensitivity to odors (hyposmia), which might not be noticed unless tested under strict laboratory conditions.
Hamsters Show Delayed but Real Smell Loss After Omicron Infection
In the study, researchers infected hamsters with either the original D614G strain of the virus or the Omicron BA.1 variant. The animals were then tested on their ability to sniff out pieces of cheese hidden at different depths in bedding. While the Omicron-infected hamsters performed better than those infected with D614G, they still struggled to locate the food compared to healthy ones—especially when the task was harder.
Omicron infection caused hyposmia by the second day post-infection. Although the olfactory (smell) tissue wasn’t immediately infected, other parts of the nasal passage showed inflammation and were filled with cellular debris, which likely disrupted airflow and odor detection.
Delayed Invasion of Smell Cells and Lingering Inflammation
Detailed tests showed that Omicron eventually reached and infected the olfactory epithelium—the layer of cells responsible for detecting smells—by the fourth day of infection. While less aggressive than earlier variants, Omicron still triggered immune cells to invade these smell-detecting tissues, causing damage.
Even eight days after infection, inflammation and immune activity in the nasal cavity remained elevated. This lingering effect may explain why some people take longer to recover their full sense of smell, or never notice it declined in the first place due to the mildness.
A Milder Yet Still Significant Threat to Our Sense of Smell
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The study concludes that Omicron does affect the sense of smell, but in less obvious ways than the earlier COVID-19 strains. Subtle changes like airflow blockage from nasal debris or immune-related interference may go undetected without proper testing. These findings suggest that the impact of Omicron on human olfactory function is likely underestimated.
The ability of Omicron to delay but eventually infect the nasal tissues, combined with reduced but persistent inflammation, highlights a hidden cost of even mild infections. Long-term consequences on sensory health could emerge over time and warrant further investigation.
The study findings were published in the peer reviewed journal: The FASEB Journal
https://faseb.onlinelibrary.wiley.com/doi/10.1096/fj.202501431RR
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