Coronaviruses such as the SARS-CoV-2 can enter the body via the nasal mucosa and may disrupt the nasal endothelium, cross the epithelial barrier, and then enter the CNS via the lymphatic or circulatory system [21]. The blood-brain barrier has a pore size of about 1 nm and coronaviruses are substantially larger [9], and this likely protects the brain from coronavirus invasion in many individuals. However, neuroinvasive viruses can cross the blood-brain barrier by brain viremia, inflammatory processes (making microvascular endothelial cells vulnerable), or infecting leukocytes that then cross the blood-brain barrier in the manner of a Trojan horse [27]. The entry of the virus via the olfactory endothelium with transit of the virus across the cribriform plate would allow the virus to enter the brain by circumventing the blood-brain barrier entirely [27].