Vaccines can be developed in a variety of ways and each of the manufacturers have made choices based on a specific focus. The goal of any vaccine is to get the body to recognize the viral invader and develop antibodies to fight it. The scientists tasked with vaccine development have used the decades of knowledge that has been learned from studying other horrendous viruses such as the flu, rabies, Zika, Ebola and H.I.V. so that the vaccines will have the highest efficacy possible. However, there are differences in both approach and development. These newer methods have allowed laboratories to create vaccines faster and in greater volumes while efficiently accomplishing the job.
mRNA COVID-19 Vaccines
The original concept of vaccines was designed to take a weakened version of the disease that wouldn’t cause harm but would trigger the body’s responses to attack a similar virus. The mRNA vaccines are “messenger RNA” and instead of using a weakened version of the virus they instruct the cells of the body to make even a small piece of the virus protein that will act to trigger the response to fight the virus through antibody production. The SARS-CoV-2 or COVID-19 virus has spikes that are on the virus’ surface that are used to enter cells. COVID-19 mRNA vaccines tell the body’s cells to create a harmless “spike protein.” As soon as the mRNA instructions are in the immune cells the cells themselves start to create these protein pieces. The original instructions are then destroyed and the body processes them as waste. At this point, the cell will place the pieces of protein on its surface as a trigger. The immune system will kick into gear as it knows that there is an invader that needs to be removed and as a response it begins to make antibodies. This is the same process that happens anytime there is an infection in the body. The instructions for mRNA vaccines are stored in a single RNA strand. Once the invader has been recognized the body will send out the appropriate antibodies anytime that infection or virus tries to invade again. The mRNA vaccines give the individual that is vaccinated the ability to fight the virus with antibodies without ever having to go through the trials and dangers of getting sick. Using a small piece of the virus protein means that even when the virus slightly mutates, the immune system will still be able to recognize it and the antibodies that have been created should continue to fight the new strain. The mRNA vaccines have had a good success rate for decades and it’s hoped that in the future scientists may be able to develop a single vaccine that addresses multiple diseases. Ongoing research has continued in the hopes that mRNA vaccines can be created to attack specific cancer cells in an attempt to eradicate that type of cancer in the body. Both the Pfizer-BioNTech COVID-19 and Moderna COVID-19 vaccines are mRNA vaccines. The Pfizer vaccine is given in two shots, 21 days apart. The Modern vaccine is given in two shots, 28 days apart.
Oxford-AstraZeneca COVID-19 Vaccine
This vaccine I known as ChAdOx1nCoV-19 or AZD1222, and was developed in a partnership arrangement between AstraZeneca, a British-Swedish company and the University of Oxford. Initial clinical trials showed that when this vaccine was given in two doses, it had an 82.4% efficacy rate. The Oxford-AstraZeneca vaccine uses the same approach as mRNA vaccines but instead of storing the instructions in a single RNA strand, the Oxford-AstraZeneca stores the instructions to emulate the virus and create antibodies in the double-stranded DNA. Another alteration is that the scientists added the coronavirus spike protein gene to a different virus called “adenovirus” which allows the virus to enter cells without the ability to duplicate themselves. In other words, they create a sterile virus. The benefit of using DNA as opposed to RNA is that RNA is much more fragile than DNA. The adenovirus has a tough protein coating that acts as a protection device for the inner genetic material. This outer coat is one of the reasons that the Oxford-AstraZeneca vaccine doesn’t have to remain in a frozen state and has a longer shelf life of six month when it’s refrigerated at 38-46 degrees Fahrenheit (2-8 degrees C).In the case of the Oxford-AstraZeneca vaccine, once it has been injected into the body the action starts happening. Once the adenoviruses come across cells it will latch onto the surface proteins. The cell encircles the virus in a bubble and when it pulls it inside the adenovirus will escape, head to the cell’s nucleus and push its own DNA into the nucleus. While the adenovirus doesn’t have the ability to replicate itself, it has the coronavirus spike protein gene that the cell reads and copies into a messenger RNA or mRNA. Another action taken by the adenovirus is that it will act to send out a warning signal to activate cells that are near it with helper “T cells.”. In essence, it turns on the alarm systems of cells that are close by. The entire Oxford-AstraZeneca vaccine process acts in a stronger manner to the spike proteins.
At this Point, the Vaccines Act Similar
Once the mRNA exits the nucleus the cell will read it and start creating spike proteins that then move to the cell’s surface and the tips will stick out. The cells that represent those that are vaccinated will additionally break up some of the pieces of the proteins and put them on the surface. The immune system will then recognize both the pieces and the spikes and activate the immune system.
Potential Problems
Although the mRNA vaccines have had excellent response to the variant strains of the COVID-19 virus, the Oxford-AstraZeneca vaccine is so new that scientists are unsure of the duration of protection that it can offer and whether the immune system memory B cells and memory T cells will retain the information about the virus.