Shingles, a painful rash caused by the varicella-zoster virus, can be prevented through vaccination. Shingrix is a vaccine developed to protect against this condition. Shingrix is not an mRNA vaccine.
The Technology Behind Shingrix
Shingrix functions as a recombinant subunit vaccine, utilizing only a specific, non-infectious component of the virus to stimulate an immune response. This vaccine contains glycoprotein E (gE), a protein found on the surface of the varicella-zoster virus. Since only a piece of the virus is used, the vaccine cannot cause shingles.
The gE component is combined with an adjuvant system known as AS01B, which enhances the body’s immune reaction. This adjuvant system comprises two main components: QS21, derived from the Quillaja saponaria Molina tree, and monophosphoryl lipid (MPL). These components are encapsulated within liposomes and work together to stimulate both antibody production and cell-mediated immunity, making the vaccine effective, especially for older adults.
Understanding mRNA Vaccines
In contrast, mRNA vaccines operate on a different principle, providing genetic instructions to the body’s cells. These vaccines deliver messenger RNA (mRNA) molecules, which contain the blueprint for producing a specific viral protein, often found on the virus’s outer membrane. The body’s own cells then read these instructions and temporarily manufacture the viral protein.
Once the cells produce the viral protein, the immune system recognizes it as foreign. This prompts the immune system to develop antibodies, without ever encountering the actual virus. The mRNA itself does not enter the cell’s nucleus or alter a person’s DNA, and it is quickly broken down by the body after the protein is made. Examples of this technology include COVID-19 vaccines, such as Pfizer-BioNTech and Moderna.
Key Differences in Vaccine Mechanisms
The fundamental difference between Shingrix and mRNA vaccines lies in what is introduced into the body and how the immune response is initiated. Shingrix directly delivers a manufactured viral protein (glycoprotein E) along with an adjuvant to boost the immune system’s recognition. The immune system encounters this protein directly and then mounts a defense.
mRNA vaccines, conversely, do not introduce a viral protein directly. Instead, they provide genetic instructions in the form of mRNA, which then directs the body’s own cells to produce the viral protein. The immune system subsequently recognizes these self-manufactured proteins and learns to defend against the virus.