July 15, 2024

New Study Reveals that All Variants of COVID-19 Can Infect the Brain

A recent study conducted by scientists from Institut Pasteur and Université Paris Cité has found that all variants of the SARS-CoV-2 virus, which causes COVID-19, have the capability to infect the brain. This study sheds light on an unanswered question regarding whether the neurological symptoms associated with COVID-19 are a result of the virus directly infecting brain cells or due to a broader inflammatory response.

Previous studies on human brain tissue have provided contradictory results, with some finding direct traces of the virus and others showing only inflammatory damage. Animal models have demonstrated that the virus can infect the brain, but studying human tissue samples is limited to post-mortem analysis, making it challenging to understand what happens during acute infections.

To investigate these unresolved questions, the researchers used a hamster model and compared the original SARS-CoV-2 virus from 2020 to subsequent variants, including Gamma, Delta, and Omicron/BA.1. The findings confirmed that all variants had similar neuroinvasive capabilities, regardless of the severity of symptoms. Furthermore, all variants infected the olfactory regions of the brain, regardless of the presence of anosmia (the loss of sense of smell).

According to lead author Guilherme Dias de Melo, this suggests that anosmia and neuronal infection are unrelated phenomena. As a result, even asymptomatic cases may involve the spread of the virus in the nervous system.

To understand how the virus infects brain cells, the researchers used a microfluidic cell culture model. This allowed them to observe how the virus travels between neurons through tiny projections called axons. The researchers found that the virus effectively exploits the physiological mechanisms of the neuron to move in both directions.

The researchers concluded that all SARS-CoV-2 variants have the ability to infect the brain through the olfactory pathway, regardless of the clinical presentation of the disease. This implies that even mild infections can lead to the infiltration of the virus into the brain.

Hervé Bourhy, another author of the study, noted that future research should explore the relationship between acute SARS-CoV-2 brain infections and the persistent symptoms seen in long COVID cases. It will be crucial to understand whether the virus can persist in the brain beyond the acute phase of infection and if its presence can induce persistent inflammation and the symptoms associated with long COVID, such as anxiety, depression, and brain fog.

This study highlights the importance of understanding the potential neurological effects of COVID-19 and emphasizes the need for further research to unravel the complexities of the virus and its impact on various parts of the body, including the brain.

1. Source: Coherent Market Insights, Public sources, Desk research
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