However, the role of aluminum in brain-based diseases remains uncertain. In these situations, health issues could be associated with the bones or brain. Most often, health issues that involve aluminum are experienced by people whose kidneys are not working well or not working at all AND who have been exposed to high levels of aluminum over a long period of time. Most of this aluminum accumulates in the bones, but about 1% of residual aluminum is estimated to accumulate in the brain. While more than half of the quantity of aluminum that enters the body is removed within 24 hours of injection, and 75% within two weeks, small amounts of aluminum, introduced either through vaccination or through the diet, may remain in the body. When aluminum salts enter the bloodstream, most are bound by a protein, called transferrin, and filtered out of the body by the kidneys.

Aluminum salts -Many vaccines contain aluminum salts to boost the response to the vaccine.

Some people wonder not about the pathogens in vaccines, but rather other components of vaccines: Therefore, the BBB is not damaged by vaccines instead, vaccines lead to protective immune responses that prevent infections and, therefore, the damage that can result from these infections. Live, weakened vaccines replicate a very limited number of times, so the tissue damage that can result during an infection does not occur. As such, they do not replicate and, therefore, cannot cause infections or damage to the BBB. Many vaccines do not contain live pathogens, but rather pieces of pathogens.

Vaccines contain versions of a pathogen that are different than the ones that cause disease. How do we know vaccine components don’t cross the BBB? Fungi and parasites can also infect the brain however, this happens more rarely than bacterial or viral infections.One example is measles virus, which can lead to a fatal condition called sub-acute sclerosing panencephalitis (SSPE). In addition, some viruses are able to infect the cells of the brain, which is more dangerous. Some examples of viruses that can cross the BBB include Japanese encephalitis virus, mumps, and rubella. While they, too, are dangerous and can be fatal, generally speaking, viral meningitis is less severe than bacterial meningitis. Examples can include Haemophilus influenzae type b, pneumococcus and meningococcus. These bacterial infections are rare, but very dangerous. Some bacteria that enter the bloodstream can cross the BBB.Meningitis and encephalitis are serious conditions that typically require hospitalization and may lead to permanent brain damage or death.ĭifferent types of germs can cross the BBB and lead to serious infections: Encephalitis - Inflammation of the brain.Meningitis – Inflammation of the meninges, the outer membrane of the brain and spinal cord.When this happens, the person may experience:

As a result of the damage, immune cells also enter the brain in an attempt to kill the invading organisms. Unfortunately, sometimes, pathogens damage the BBB, enabling them to leave the blood and enter the brain. Typically, cells of the immune system are not able to cross the BBB. Glucose and other nutrients necessary to keep the brain healthy and functioning properly are allowed to cross the BBB and enter the brain. The BBB is very restrictive, limiting what can access the brain. View this video with a transcript What can cross the BBB and enter the brain? In this manner, cells of the BBB act as a gate, limiting which substances gain access to the brain, thereby protecting it from pathogens and other harmful substances while still allowing nutrients to enter the brain and keep it healthy. As a result, in order to access the brain, substances must pass through, or interact directly with cells that form the BBB. The BBB is composed of cells that are closely linked together, forming “tight junctions.” These junctions prevent substances from passing between cells and into new locations, such as the brain. The BBB is a membrane the separates the brain from the rest of the body. Importantly, our brains are protected by a barrier, called the blood-brain barrier (BBB), which keeps foreign substances from entering the brain. In order to affect the brain, vaccine components would need to reach the brain. Some people concerned about vaccine safety wonder whether vaccines may enter the brain and cause neurological conditions.

Blood brain barrier function