Japanese Study Finds 35.5 Percent of Omicron Cases Develop Long COVID, Debunking Milder Variant Myth
Nikhil Prasad Fact checked by:Thailand Medical News Team Mar 20, 2025 12 hours, 48 minutes ago
Medical News:
Study Challenges Assumptions About Omicron’s Impact
For years, many believed that the Omicron variant of SARS-CoV-2 caused milder illness compared to earlier strains of the virus and that there was little chances of developing Long COVID from exposure to it and all the so called “milder strains” thereafter. However, new research conducted by scientists from Nagasaki University Graduate School of Biomedical Sciences and Nagasaki University Hospital, Japan has revealed that Omicron can still lead to persistent, long-term health issues. According to their findings, 35.5 percent of individuals who experienced mild COVID-19 during the Omicron wave developed long COVID symptoms lasting for more than 12 weeks.
Japanese Study Finds 35.5 Percent of Omicron Cases Develop Long COVID, Debunking Milder Variant Myth
This
Medical News report underscores the ongoing public health challenge posed by long COVID, even as the world moves toward managing COVID-19 as an endemic disease. Despite Omicron’s reputation as a “mild” variant, these findings suggest that a significant portion of patients continue to experience lingering effects, challenging previous assumptions that less severe illness translates to lower risks of long COVID.
The Study: Methods and Key Findings
The study was conducted through an online survey targeting outpatients diagnosed with mild COVID-19 at 14 participating institutions across Japan between July 30, 2022, and December 31, 2023. Researchers analyzed 246 cases where patients reported their symptoms at 12 weeks post-infection.
Key Findings:
-35.5% of individuals reported at least one long COVID symptom after 12 weeks.
-Respiratory symptoms (such as chronic cough and shortness of breath) were present in 18.7% of patients.
-Neurological symptoms (including brain fog, dizziness, and difficulty concentrating) affected 15.9%.
-Psychological symptoms (such as anxiety and depression) were reported by 16.8%.
-Fatigue was prevalent in 15% of cases.
-Pain and hair loss were reported in 8.9% and 7.5% of cases, respectively.
Risk Factors for Long COVID
The study identified certain risk factors that increased the likelihood of developing long COVID symptoms.
-Age: Individuals aged 40 years and older were significantly more likely to experience respiratory and neurological symptoms.
-Antiviral Drug Use: Patients who used antiviral drugs during their initial COVID-19 infection had a lower risk of developing persistent respiratory symptoms. The study found that antiviral treatment was associated with a 69% reduction in respiratory complications.
These findings suggest that older individuals need closer medica
l attention even if their initial Omicron infection was mild. Moreover, antiviral drugs may play a role in reducing the severity of long-term respiratory symptoms, emphasizing the importance of early intervention.
Implications for Public Health
While Omicron has been considered a milder variant, this study highlights the substantial burden of long COVID that persists even after mild infections. The fact that over one-third of Omicron-infected individuals developed long-term symptoms means that healthcare systems must prepare for ongoing medical care and rehabilitation for affected patients.
The study also supports the proactive use of antiviral treatments to mitigate the risk of long COVID, particularly for high-risk groups. As long COVID can impact daily activities, work productivity, and overall well-being, it remains a major public health concern worldwide.
Conclusion
This research findings challenge the misconception that Omicron does not contribute significantly to long COVID cases. The study clearly demonstrates that 35.5% of individuals with mild Omicron infections develop persistent symptoms, particularly respiratory and neurological issues.
Patients aged 40 and above are at higher risk, and early antiviral treatment may reduce respiratory complications. Healthcare professionals should remain vigilant in monitoring and managing long COVID symptoms to ensure better long-term health outcomes for patients.
The study findings were published in the peer-reviewed journal: Respiratory Investigation.
https://www.sciencedirect.com/science/article/abs/pii/S221253452500019X
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Read Also:
https://www.thailandmedical.news/news/study-surprisingly-finds-omicron-variant-causes-more-serious-issues-in-infants-children-and-teens-compared-to-delta
https://www.thailandmedical.news/news/austrian-study-finds-that-sars-cov-2-omicron-strains-exhibits-greater-cardiotropism-than-previous-variants
https://www.thailandmedical.news/news/study-reveals-neurological-dangers-of-mild-omicron-subvariants
https://www.thailandmedical.news/articles/coronavirus
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