This refers to the examination and study of where the vaccine and its ingredients go once injected into the body. Having sped up the approval process of these vaccines, it has been claimed that no compromises in the process of examining their safety were made. But the fact that no study for tracking the distribution of the vaccine within the human body was conducted for any of the authorized vaccines, we cannot say this is true.
Dr. Doshi points out that such bio-distribution studies are a standard practice of drug safety testing but "are usually not required for vaccines." This in itself is concerning. Research regarding the bio-distribution of aluminum containing vaccines, for example, have raised concerns about injected aluminum crossing the blood brain barrier and being distributed throughout the body where it can be detected years after injection. This is important, because vaccines are a different method of delivery than say, ingested aluminum, which the body does a great job of getting rid of through digestion.
Bio-distribution studies weren't performed for COVID vaccines because data from past studies performed with related, and "mostly unapproved compounds that use the same platform technology" were used to bypass them.
Dr. Doshi points out that,
"Pfizer and Moderna did not respond to The BMJ's questions regarding why no biodistribution studies were conducted on their novel mRNA products, and none of the companies, nor the FDA, would say whether new biodistribution studies will be required prior to licensure."