COVID-19 can enter the brain via the nose.

Further COVID-19 studies that include a broad range of sampling are needed to identify the precise mechanisms which leads to the virus' entry

Further COVID-19 studies that include a broad range of sampling are needed to identify the precise mechanisms which leads to the virus' entryA team from Germany demonstrated that SARS-CoV-2 has developed an ability to enter host cells by interacting directly with angiotensin-converting enzyme-2 (ACE-2), widely expressed in various tissues, including the brain. The study assessed olfactory mucosa, its nervous projections, and several defined CNS regions in 33 individuals who died in the context of COVID-19.

The study conducted by researchers from Charite-Universitatsmedizin Berlin, Germany, was published in Nature Neuroscience. It revealed that the novel coronavirus might enter the human brain through the nose. According to the study, SARS-CoV-2 or COVID-19 virus affects the respiratory tract and impacts the central nervous system (CNS), resulting in neurological symptoms such as loss of smell, taste, headache, fatigue, and nausea.

The researchers found that SARS-CoV-2 spike protein in certain cells within the olfactory mucous layer may exploit the proximity of endothelial and nervous tissue and enter the brain. In some patients, SARS-CoV-2 spike protein was found in cells, suggesting that olfactory sensory neurons may be infected in the brain areas that receive smell and taste signals. The virus was also found in other nervous system regions, including the medulla oblongata, the brain's primary respiratory and cardiovascular control center.

Also, of the 33 autopsy patients, 60.6 percent (20 of 33) showed evidence of SARS-CoV-2 RNA in olfactory mucosa—the lining of the nasal cavity containing sensory nerve endings for the smell. However, further COVID-19 studies that include a wide range of sampling are needed to identify the specific mechanisms that mediate the virus's entry into the brain.

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