After a year of illness, social disruption, and economic pain, Americans finally have a chance to regain control over a virus that has claimed hundreds of thousands of lives. Vaccines were once viewed by Americans as saviors over diseases that inflicted suffering and death across all corners of our country. But with the rise of social media, some people have become leery of vaccines. Let’s take a step back before discussing the current COVID-19 vaccines.
Through the mid-20th century, parents feared paralysis and death each summer as polio epidemics spiked, and at all times of the year pregnant women dreaded the horrific birth defects caused by rubella (German measles) including brain damage, deafness, blindness, and stillbirth. These are just two of the many infectious diseases (whooping cough, meningitis, measles, etc.) that caused serious illness and death across the U.S. on a regular basis. When vaccines were developed to prevent these diseases, it was seen as patriotic to voluntarily step up and receive inoculation. Americans were not only protecting their families,
but their entire communities.
Vaccines traditionally worked by introducing dead or inactivated virus or bacteria into the body so the germ could be recognized by the body’s immune system with little risk of causing harm. During a natural infection, it typically takes a week or more for the body to fully mount a response to a new pathogen. By that time, severe illness can develop. A vaccine allows the body the opportunity to develop an immune response prior to the threat of actual infection. The vaccine stimulates the production of antibodies and cytotoxic (“killer”) T cells that can be quickly summoned by our bodies if we are infected by the live virus or bacteria later on. The antibodies and killer T cells prompted by the vaccine will activate within hours after exposure to an actual infection. This quick immune response prevents both illness and the potential that vaccinated people will spread the disease to others.
The two vaccines approved by the FDA use a newer technology to produce a robust immune response to the virus responsible for COVID-19. Although these are the first mRNA vaccines approved, this technology has been undergoing steady research and development for the past 30 years. Recent advances have provided the means of stabilizing the lipid nanoparticle coating that delivers the key piece of antigenic material to our cells. If that sounds like too many technical terms and you want more understanding, please read the next three paragraphs. Otherwise, feel free to skip past the second diagram.
Messenger RNA (mRNA) is a molecule produced by our cells to translate inherited genetic information from our DNA into actual proteins our bodies need to function. You couldn’t digest your food, read this article, or breathe without DNA being transcribed to mRNA which is then translated into the proteins we need to survive. The COVID vaccines use this mRNA-to-protein translational process to eliminate the need to inject whole viruses that were necessary in older generations of vaccines. Based on the genetic code of the COVID virus, researchers were able to identify the genes that code for a key protein on the virus’s surface (spike protein). This specific segment of genetic material, and only this specific segment,
was transcribed into a piece of mRNA to be used for vaccination. Because the vaccine only contains this one portion of mRNA, there is no risk of COVID infection from either vaccine.
The final technical barrier to produce a successful vaccine has been to protect the fragile segments of mRNA until they can be delivered inside cells to ribosomes. Ribosomes are tiny assembly factories in our cells’ cytoplasm that translate the instructions encoded in mRNA into protein (see diagram below). Recent scientific breakthroughs have led to the development of protective envelopes (lipid nanoparticles) that transport mRNA through cell membranes and release it into the cytoplasm. Lipid nanoparticles also have a very short half-life, so within a few days of administration, all of the vaccine mRNA is gone.
The left side of the following diagram corresponds to the mRNA vaccine process (the right side is for a different type of vaccine that is still under development):
Pharmaceutics, 2020, 12(2), 102
From there, the vaccine-driven cells (via antigen presenting cells and T-helper cells) deliver COVID spike proteins to the B cells and cytotoxic T cells of our immune system (see diagram below). B cells are then produced to generate specific antibodies against the COVID virus, and cytotoxic T cells are programmed to destroy any cells that are initially infected with COVID virus before the virus can spread throughout our bodies. This combination of antibody and T cell protection has shown to be 95% effective in preventing COVID infections in those who have received the recommended 2-dose mRNA inoculation.
Nature 580 576-577 (2020)
Because the COVID vaccines only contain two critical components (mRNA and lipid nanoparticles), the potential for side effects is likely lower than for traditional vaccines. The independent panel of experts who reviewed the most recent vaccine for the FDA voted 20-0 that the benefits of the mRNA vaccine clearly outweighed risks. However, these are new products and it would be disingenuous to suggest there is no potential for adverse reactions. Each vaccine was administered to 15,000 people, along with 15,000 people receiving placebo injections, starting in July. In addition, over 200,000 frontline healthcare workers have thus far received the Pfizer vaccine. Overall, three cases of anaphylactic allergic reaction have occurred with the Pfizer vaccine. Allergic reactions have not been seen yet with the Moderna vaccine. There are no preservatives in either vaccine and neither were made with any egg products. As a precaution, people with a history of anaphylactic reactions should make sure they receive vaccination at a l