Social media users are sharing posts which claim that coronavirus tests damage the hematoencephalic barrier, or the blood-brain barrier, allowing bacteria that accumulates in face masks to inflame the brain. This claim is false. Public Health England confirmed to Reuters that it is not anatomically possible for nasal swabs used in COVID-19 tests to reach the blood-brain barrier.

The posts ( here , here , here ) show an image of a swab inserted through the nose, accompanied by three further images where the position of the brain is highlighted to show that the top of the swab touches the edge of the brain.

The text accompanying one of the most-shared posts reads, “The corona test has a completely different purpose than the one you believe in or are being told about. Insertion of the wand very deep into the nasal cavities damages the hemato-encephalitic [sic] septum in the depth of the skull That [sic] is why testing is so painful. “

“The goal of this in-depth test is to damage the hemato-encephalitic [sic] barrier and thus provide immediate access to the brain to be susceptible to any influence. Watch out! This effect comes from wearing masks, from bacteria that accumulate on masks and easily leads to inflammation of the brain.”

Hematoencephalic means the interface between the bloodstream and the brain. The blood-brain barrier, formerly known as the hematoencephalic barrier, filters out drugs and other substances in the blood so they cannot reach the brain. If the blood-brain barrier is broken, the brain may be exposed to toxins, which may be an important factor in long-term brain changes ( here )

The long swab described is a nasopharyngeal swab, which is one of the COVID-19 testing methods recommended by the U.S. Centers for Disease Control and Prevention (CDC) ( here ) .

A spokesperson for Public Health England told Reuters that it is not anatomically possible for these swabs to take samples from the blood-brain barrier: “There is no point in the respiratory tract or nasal cavity where the brain is accessible. It would not be possible to touch the brain with a swab without drilling through the cribriform plate.”

The cribriform plate forms the roof of the nasal cavity ( here ).

Nasopharyngeal swabs do not touch the cribriform plate; instead, they are inserted parallel to the nasal floor to take samples from the nasopharynx, which is found between the base of the skull and the soft palate (here), as shown in this video youtu.be/1H759HE7y50 from the 32-second mark. The Rush Medical Center doctor specifically says that it is important not to veer upwards towards the critical structures in the nose.

Nasal swabs should not hurt, according to UK government advice ( here ).

Reuters recently debunked similar claims relating to nasopharyngeal swab COVID-19 tests and the blood-brain barrier ( here , here ) .

False. It is not anatomically possible for COVID-19 tests to collect samples from the blood-brain barrier; instead they take samples from the nasopharynx.

This article was produced by the Reuters Fact Check team. Read more about our work to fact-check social media posts here .

Our Standards: The Thomson Reuters Trust Principles.

All quotes delayed a minimum of 15 minutes. See here for a complete list of exchanges and delays.