The brain is normally protected by the blood brain barrier, a sort of tightly meshed network that lets only the smallest molecules filter through, so as to prevent the passage of germs and toxic substances.

Since neurological and psychiatric symptoms (loss of taste and smell, headache, dizziness, seizures, disturbances in consciousness, ischemic or haemorrhagic stroke, etc.) are frequent in patients with Covid, it is evident that the virus has succeeded to cross this network, reaching the brain tissue via the blood.

Another route of access traveled by the virus is represented by the olfactory nerves, which it goes back up to reach the brain bulbs.

Once it has settled in the brain it can immediately manifest its presence with the symptoms described above, or remain silent to wake up even after years and cause new damage, similar to what happened in post-encephalitic Parkinson’s, told in the famous book Awakenings by Oliver Saks. This could also happen in people who have had Covid asymptomatically.

It is therefore important to have an antiviral drug that is effective on SARS-Cov2 (this is the name of the virus responsible for Covid-19) and that is capable of crossing the blood brain barrier.

Hydroxychloroquine 21%
Baricitinib 20%
Ruxolitinib 3,5%
Remdesivir <5%
Tocilizumab 0,1%
Lopinavir/ritonavir 0,02%
Favipiravir 0,01%

Table: Drugs tested in Covid: percentage that manages to pass from the blood to the brain. It is observed that they pass in small quantities, and their effectiveness against Sars-Cov-2 is however modest or null even in full doses.

Methylene blue: passes smoothly.

The images that can be seen at this link can speak themselves: