Vaccine Development - Safety, Speed, and Types

    The vaccines for COVID-19 have broken all previous records for the fastest development till distribution - going from development to approval in a matter of months. While the vaccine for Mumps took 4 years for development, 13 years for polio and 27 years for the flu, most COVID-19 vaccines are developed only in a year. This speed is driven by global efforts and billions of dollars. In some cases, it is also because of breakthroughs in vaccine technology, decades in making: something that could shrink this timeline going forward, and change how vaccines are developed altogether.

    Vaccines educate the immune system on how to respond in the event of a threat. There have historically been four ways of accomplishing this. The two most common approaches include exposing your immune system to a weakened (Live-Attenuated) or dead (Inactivated) form of the virus or bacteria, which will not make you sick but will teach your body how to combat the actual pathogen if you are exposed to it later. Another, less common type of vaccine performs the same role but instead of a virus, uses an inert variant of a toxin. The tetanus shot is the most well-known example of this toxoid vaccine. The fourth type of vaccine varies from the first three in that it only uses small sections of a virus rather than the whole virus. The best example of this vaccine type is the Hepatitis B vaccine.

    Some of the recent vaccines for COVID-19 use the 4th type. The spike proteins on the virus aid the virus's entry into your cells. It is completely safe when inserted into the body on its own. However, the immune system can always recognise it as a foreign threat and activate an immune response to combat it. This is sufficient to teach the body how to combat the entire virus. Isolating and storing only the spike protein for a vaccine, on the other hand, takes a long time. Researchers had to alter it, multiply it by a lot, and assemble the vaccine in a lab. This necessitates the laboratory cultivation and transportation of large quantities of pathogens. It's clear that it is a long process. And this is just the development process. Creating a vaccine is much more than developing it - they need to send it for preclinical trials, different phases of human trials, licensing, manufacturing, and then distribution. It takes an average of 5-10 years for a vaccine to pass the stage of approval. Most COVID-19 vaccines have sped up the process by combining various phases of human trials and beginning production early, while others have found a way to speed up the development process by moving some of the work out of the lab and into your body.

    Proteins perform nearly all of our body's functions, and our cells are actively producing them. They do this by making a single-stranded copy of DNA known as a messenger RNA or mRNA. Each strand of mRNA contains instructions for producing a specific protein. To put it plainly, the cell reads the mRNA, follows the instructions, and produces proteins. This is where two new types of vaccines come into action. They have instructions in them. The production of an mRNA vaccine begins with the virus's genetic sequence. It also concentrates on the spike proteins we discussed earlier. Rather than assembling and purifying the protein in the lab, they found the part of the genetic sequence that codes for the spike protein's synthesis. Then, by synthesising mRNA and using it as a vaccine, months of time and money were saved. Once within the body, the cells read the mRNA and start making their own harmless spike proteins. The immune system of your body then detects the danger and raises the alarm. This is how Pfizer-BioNTech and Moderna's new COVID-19 vaccines work. The biggest disadvantage of this mRNA vaccine is that mRNAs are quickly broken down. It must be delivered within a safe fatty barrier and kept extremely cold, which is impractical for a vaccine that must be distributed worldwide. Another new-to-consumer vaccine acts in a similar way, but instead of mRNA, it uses DNA, which is much more stable. This is the case for both AstraZeneca's and Johnson & Johnson's COVID-19 vaccines - where they used a modified version of a chimpanzee adenovirus, known as ChAdOx1, as a vector to carry the gene coding for the coronavirus' spike protein. During storage and transportation, these vaccines do not need ultracold temperatures. In any case, these two new types of vaccines have set new records in terms of effectiveness, cost, and speed. They are a modern technique of eliciting an immune response. Although they have a significant influence on how we combat COVID-19, their true impact is just getting started. The creation of these vaccines is a watershed moment in the pandemic, and through effective vaccination protocols in nations all over the world, this could lead to a huge global public health victory in modern times.