mRNA vaccines: a primer

MRNA vaccines. It seems like they're always in the news. Why? Health Secretary RFK jr. and the current administration are on a crusade against the technology, claiming it is harmful more than it helps people. Do people really understand how it works? Probably most people don't. So here is a primer on how they work along with any risks involved.

Messenger RNA (mRNA) vaccines represent a breakthrough in immunization technology, offering a highly effective way to prevent infectious diseases such as COVID-19. Unlike traditional vaccines, which often rely on weakened or inactivated viruses or pieces of the virus, mRNA vaccines work by instructing the body’s own cells to produce a harmless piece of the virus—typically a protein—that triggers an immune response.

At the core of this process is the use of synthetic mRNA, a type of genetic material that carries instructions for making proteins. In the case of COVID-19 vaccines like Pfizer-BioNTech and Moderna, the mRNA encodes the instructions for making the virus’s spike protein—the part of the virus that allows it to enter human cells. Once injected, the mRNA is absorbed by cells, usually in the muscle near the injection site. These cells read the mRNA’s instructions and begin producing the spike protein. Importantly, the spike protein produced is not infectious; it cannot cause disease. However, its presence alerts the immune system to a potential threat. The immune system responds by producing antibodies and activating specialized cells that remember the spike protein. This memory equips the body to recognize and rapidly neutralize the real virus if it is encountered in the future.

The mRNA used in these vaccines is quickly broken down by the body after the spike protein is made. It does not enter the nucleus of the cell, where DNA is kept, and therefore cannot alter a person’s genetic code. Because of this, mRNA vaccines are considered safe and do not carry the risk of causing disease from the vaccine itself.

The speed with which mRNA vaccines can be developed is another major advantage. Scientists can quickly design new mRNA sequences in response to emerging viral threats, making this technology a promising platform for future vaccine development, not just against infectious diseases but potentially for cancer and other conditions as well.

Understanding mRNA

The first step of understanding mRNA vaccines is to understand how mRNA works normally in a human cell. We can visualize this as follows:

Step 1: DNA exists. This will be the blueprint for mRNA.

Step 2: mRNA is a copy made from the original DNA. It is an intermediate that will be the code for a protein.

Step 3: A protein is created from the code contained in the mRNA. This occurs at the ribosome.

Let's take this further. An mRNA vaccine is a dose of pieces of mRNA (in Step 2) which encode the information to produce a protein that resembles part of the virus that is being targeted (Step 3). Essentially, this cuts out Step 1 in which DNA is used to make mRNA. The protein that is produced is designed to be recognized by the body, setting off an immune response targeting that particular target. If you design the resulting protein to look like part of a virus, your body will start producing antibodies to the virus (as seen in Step 4 and 5).

Resulting in Step 4: Your body starts recognizing this protein at foreign and...

Step 5: Specialized cells start producing enough copies of the antibody to neutralize the virus.

Note one important thing: The mRNA DOES NOT become part of your body's DNA because it only flows in one direction (like Harry Styles) and the mRNA is downstream of the DNA. So, fears that mRNA somehow changes your body's DNA either permanently or temporarily are completely false. No mutations are possible, and the human body breaks down what is left of the mRNA with proteases (other proteins designed to break down old proteins).

The other major (and very legitimate) fear is that the side-effects are more harmful than the actual disease it is designed to fight. However, the data shows that this is unlikely.

The most serious side-effect of mRNA vaccines is the chance of anaphylaxis, a very serious immunological overreaction to the presence of an antigen. This is the same effect that beestings or peanuts have on highly allergic people. This occurs in 2.5 people per million. Normal vaccines have been found to have a rate of about 1.3 per million. So, it is possible that the risk is slightly higher, but still quite small. If the entire USA got the vaccine, 855 people would be expected to have this reaction from an mRNA vaccine. In fact, most reactions seem to be in line with risks from traditional vaccines.

What are the positives of using an mRNA vaccine compared with other vaccines? Essentially, speed and specificity. The speed of developing a new vaccine for a new type of virus was what allowed a new covid-19 vaccine to be developed much quicker than other types could have been. The specificity refers to the vaccine's ability to create a target that is effective for that one virus instead of creating a target that makes the body produce antibodies that cross-react with the body's own cells.

mRNA Vaccines in Cancer Treatment

Added to the is the promise the vaccines based on mRNA technology have shown in other disease treatment, such as treatment of cancers. mRNA vaccines are being explored as a promising approach in cancer treatment by harnessing the immune system to recognize and destroy cancer cells. Unlike infectious disease vaccines, which train the immune system to recognize viral proteins, cancer mRNA vaccines are designed to encode tumor-specific antigens—proteins found predominantly on cancer cells but not on healthy tissue. Once the mRNA is delivered into the body, usually via injection, cells take up the instructions and begin producing these cancer-related antigens. The immune system then identifies these antigens as abnormal and mounts a targeted immune response, including the activation of cytotoxic T cells that seek out and destroy tumor cells expressing the same proteins. This personalized immunotherapy approach allows mRNA vaccines to be tailored to the unique genetic mutations of an individual’s tumor, potentially improving treatment outcomes and reducing harm to normal tissues. Clinical trials are ongoing, and early results suggest that mRNA cancer vaccines may become a valuable tool in the broader field of oncology.

Check out this exciting new research in mRNA cancer vaccines:

An mRNA vaccine to treat pancreatic cancer | National Institutes of Health (NIH)