Can COVID-19 Nasal Swab Tests Damage the Blood-Brain Barrier?

A tweep shared the image above with a claim warning that COVID-19 swab tests damage the blood-brain barrier.


At present, polymerise chain reaction (PCR) and antibody testing are the dominant ways being used globally to test people for Covid-19. The PCR test (nasal swab test) is a technique that directly detects the virus in a person’s nasal secretions or saliva.

The tests typically take several hours, including specimen-processing time, to generate results and require laboratory equipment and trained technicians. PCR tests are currently considered to be more clinically sensitive for detecting early infection.


During a COVID-19 swab test, the person conducting the test will insert a long stick with a very soft brush on the end up your nose and twirl it around for a few seconds. The soft bristles will collect a sample of secretions there for analysis. The swab has to go far back because cells and fluids must be collected from along the entire passageway that connects the base of the nose to the back of the throat to get a really good specimen. The test can, however, cause discomfort. For instance, it activates the lacrimal reflex, which means it’ll bring tears to your eyes if it’s done correctly and since the swab will also touch the back of the throat, it may also trigger a gag reflex.

The blood-brain barrier is a selectively permeable membrane that regulates the passage of a multitude of large and small molecules into the microenvironment of the neurons. It achieves this with the aid of multiple cellular transport channels scattered along the membrane. This filters toxic substances in the blood so that they cannot reach the brain. It is correct that 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.

COVID-19 swabs are taken from the upper respiratory tract, where the nasal cavity is. It would be, anatomically, impossible to touch the brain with a swab without drilling through the cribriform plate. The cribriform plate, which is sieve-like to allow passage of olfactory nerves that conveys special sensory information related to smell, forms the roof of the nasal cavity.


COVID-19 nasal swab tests do not touch the blood-brain barrier, making the claim FALSE.

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