Nikhil Prasad Fact checked by:Thailand Medical News Team Feb 02, 2026 1 hour, 39 minutes ago
Medical News: A major new scientific study has revealed how COVID-19 can silently persist and evolve inside people with severely weakened immune systems, sometimes for months or even years, raising important concerns about long-term infection risks and the possible emergence of new viral variants. This
Medical News report explores findings that are both alarming and critical for public health awareness.
Study reveals how COVID-19 can silently persist and mutate for years in people with severely
weakened immune systems
Understanding Persistent COVID-19 in Vulnerable Patients
Researchers closely examined three immunocompromised patients who were unable to fully clear the SARS-CoV-2 virus from their bodies. These included a cancer patient treated with immune suppressing drugs, a man with advanced untreated HIV infection, and a woman with Good’s Syndrome linked to thymoma. Unlike typical COVID-19 cases that resolve within weeks, these patients continued to test positive for active virus for periods ranging from nine months to more than four years.
How The Virus Keeps Replicating
Using repeated PCR testing and advanced whole genome sequencing, scientists confirmed that the virus was not dormant or inactive. Instead, it continued replicating inside the body, producing new viral particles over time. The detection of sub-genomic RNA, a marker of active viral replication, showed that the virus was continuously alive and evolving rather than leftover genetic fragments from an old infection.
Viral Evolution Inside the Body
One of the most striking discoveries was that the virus accumulated mutations while lingering inside these patients. In the patient with advanced HIV, the virus developed multiple changes in the spike protein, including mutations seen in known variants of concern such as Omicron and Delta. These changes are associated with immune escape and increased transmissibility. In contrast, patients with little immune pressure showed fewer spike mutations, suggesting that partial immune responses may actually drive viral evolution.
Why Immunocompromised Patients Are Different
People with weakened immune systems often cannot produce strong antibody responses, either due to disease or treatments like rituximab that deplete B cells. This creates an environment where the virus can survive longer, replicate freely, and gradually change. The study highlights that persistent COVID-19 is distinct from long COVID, as it involves ongoing infection rather than post-viral symptoms.
Institutions Behind the Research
The research was conducted by scientists from the Instituto Nacional de Cancerología, Instituto Nacional de Enfermedades Respiratorias Ismael Cosio Villegas, Universidad Nacional Autónoma de México, and associated molecular biology and immunology laboratories in Mexico City.
Why These Findings Matter
The
study strongly suggests that persistent SARS-CoV-2 infections in immunocompromised individuals may serve as hidden reservoirs for viral evolution. This has serious implications for infection control, treatment strategies, and surveillance, especially in hospital and community settings. Early identification and aggressive antiviral treatment could help reduce prolonged viral replication and lower the risk of new variant emergence.
Conclusions
These findings clearly demonstrate that in people with severely weakened immune systems, COVID-19 can persist far longer than previously assumed, actively replicating and mutating inside the body. This prolonged infection not only endangers individual patients but also poses a broader public health concern. Continuous monitoring, targeted antiviral therapies, and specialized care strategies are urgently needed to prevent long-term viral evolution and reduce the risk of future outbreaks linked to persistent infections.
The study findings were published in the peer reviewed journal: Viruses
https://www.mdpi.com/1999-4915/18/2/189
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Read Also:
https://www.thailandmedical.news/articles/coronavirus
https://www.thailandmedical.news/articles/long-covid
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