Researchers from Tulane University have examined how the two viruses affect the body over the long term.
The findings have been published in the journal Frontiers in Immunology.
In an experiment involving mice, the researchers found that animals infected with SARS-CoV-2 (COVID-19) showed signs of brain inflammation several weeks after the virus was no longer detectable.
Small hemorrhages were also found in the brain’s fine blood vessels.
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At the same time, analyses revealed changes in systems that influence mood, energy, and concentration.
These changes were largely not observed in mice that had been infected with influenza.
Impact on the lungs
Both infections left traces in the lungs. The researchers observed an increased amount of collagen, which can make lung tissue stiffer.
There was also continued activity in the immune system even after the infection had resolved.
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This may help explain why some people experience shortness of breath in the period following illness.
However, there was an important difference. After influenza, the lungs initiated a clear repair process.
According to the researchers, this response was far less pronounced following COVID-19.
Implications for long-term effects
The aim of the study was to determine whether long-term effects are caused by general reactions to severe respiratory infection or whether COVID-19 has distinct consequences.
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According to lead researcher Xuebin Qin, both influenza and COVID-19 affect large population groups globally and place a significant burden on public health, yet there is still a lack of knowledge about the biological mechanisms behind their long-term effects.
The findings suggest that COVID-19, to a greater extent than influenza, may cause persistent effects on the brain.
This may help explain symptoms such as fatigue and difficulty concentrating in some patients.
Sources: Medical Xpress, and Frontiers in Immunology.
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