Current Vaccines Utilize Spike Protein

Most Covid-19 vaccine candidates—including mRNA, DNA, viral vector, recombinant protein, viral-like particles, and peptide-based vaccines—are designed to elicit immunity based on the SARS-CoV-2 spike protein.

• The Pfizer-BioNTech and Moderna mRNA vaccines comprise mRNA genetic material encased in LNPs, which fuse with muscle and immune cells when injected. This allows the mRNA to instruct cells to produce spike proteins, triggering an immune response.
• The AstraZeneca-Oxford and Johnson & Johnson adenoviral vector vaccines employ a harmless modified adenovirus to deliver DNA encoding SARS-CoV-2 spike proteins.
• The Novavax vaccine uses purified spike proteins to stimulate an immune response.
• The Sinovac and Sinopharm vaccines utilize inactivated SARS-CoV-2 virions to induce immunity.

Although all these vaccines rely on spike proteins, only the mRNA vaccines employ innovative LNP technology for cellular delivery.

Lipid Nanoparticles (LNPs) and Their Hypothetical Risks

Administered via intramuscular injection, mRNA vaccines effectively reach the bloodstream due to the high vascularity of muscle cells. LNPs facilitate the entry of mRNA into mammalian cells, enabling the vaccine to potentially access various cell types, including neurons in the brain and spinal cord.

LNPs are often utilized to navigate the blood-brain barrier (BBB), which typically restricts the entry of medical treatments into the brain. As a result, there is concern that brain cells expressing spike proteins may be recognized as foreign by the immune system, potentially leading to attacks by cytotoxic T-cells. Unlike other cell types, neurons have limited regenerative capabilities.

Dr. Jacob Wes Ulm, a geneticist, has articulated these concerns in detail, noting that mRNA vaccines may expose a broader range of cells to cytotoxic effects compared to traditional vaccines. He expressed frustration regarding the lack of comprehensive data on the distribution of LNPs within the body, emphasizing the need for clarity on where these particles migrate.

A 2017 study found traces of mRNA in the brains of vaccinated mice, while significantly higher concentrations were detected in muscles and lymph nodes. The European Medicines Agency's (EMA) report on the Moderna vaccine corroborated that low levels of mRNA were present in various tissues, including the brain, but these levels were minimal.

While some experts have raised questions about the potential for LNPs to infiltrate critical cells, such as oligodendrocytes or neurons, the actual implications of such occurrences remain unclear.

Potential Benefits of LNPs

Several studies have explored the cellular distribution of LNPs carrying mRNA. Research indicates that intramuscular administration primarily targets the liver, muscles, spleen, and lymph nodes. While some traces of mRNA were found in the brain, it does not appear to be a primary target for LNPs.

Dr. Goh Kiang Hua has argued that the mRNA vaccine is unlikely to reach the brain due to numerous barriers along the way. The LNPs must navigate through densely packed muscle cells, enter the lymphatic system, and withstand the heart's pumping action. The BBB further complicates this process, as it may absorb the mRNA before it can reach the brain.

Even if LNPs successfully penetrate the BBB, the fate of the mRNA within the brain is uncertain. It may degrade, or neurons may express spike proteins, potentially inciting an immune response. However, the regulatory mechanisms governing T-cell entry into the brain suggest that significant neuronal damage from such an event is improbable.

The mRNA from vaccines does not persist long within cells, typically degrading after a few days. Moreover, ongoing monitoring of vaccine trial participants has not revealed any long-term health issues.

Conclusion

In summary, while there are legitimate concerns regarding the potential for LNPs to deliver mRNA to unintended locations within the body, the consensus among health authorities and researchers is that the risks posed by SARS-CoV-2 infection are significantly greater. The complexities of human biology often mean that theoretical risks do not always translate into real-world effects.

The discussion surrounding mRNA vaccines is ongoing, and there is a strong call for further research to address these concerns. The focus should remain on the broader context of the threats posed by Covid-19, particularly for vulnerable populations.

Thanks to the mRNA discussion group, including William Stewart, Ph.D., Goh Kiang Hua, MD, Christopher Shaw, Ph.D., and J. Wes Ulm, MD, Ph.D., and Steve Pascolo, Ph.D., for their invaluable insights into this matter.