The battle to fight against COVID is still ongoing, but that shouldn’t discourage us from the fact that we have made great strides already. This battle has seen vaccine development move at record speed, with around 200 vaccines in trials.
As of December 2020, about 200 vaccines are in development. With, around 52 ready for human trials. In addition, the vaccine drive has been going on successfully, with about 7.7 percent of India’s population vaccinated in the first month itself.
All the vaccines are on the mission to achieve the same thing: immunity from the virus. But then, why are there so many vaccines in development? And which one is the most effective? Keep watching to know more.
In today’s video, we have provided a detailed guide on the different COVID vaccines and how they work.
Also, read Post Covid Syndrome : Know Its Symptoms
Why are there so many vaccines in development?
Typically, to deal with a pandemic on a large scale, many candidate vaccines have to undergo human trials to evaluate that they are safe and effective. For example, roughly only about 7 out of 100 vaccines that are tested in the laboratory and on lab animals are considered safe enough to move on to clinical trials. The vaccines that make it to the clinical trials are then tested on humans and only one in five is found to be useful.
Having different vaccines in development ensures that the process is going to be fast and smooth, and soon, the most effective and safe vaccine will be available.
This is why there are over 200 vaccines in development currently.
Different types of vaccines
There are three approaches to developing a vaccine. What is different in all three? The approach with which these vaccines are developed. Some have used a whole virus bacterium or just the part of the germ that triggers the immune system, or the genetic material that provides guidelines for making specific proteins (and not the whole virus).
1.The Whole-Virus or Whole-Microbe approach
- Inactivated vaccine
The first step of developing any vaccine is to take the disease-carrying bacteria or virus (or, one that is most similar to it), and inactivate it or kill it using heat, chemicals, or radiation. This approach of vaccine uses technology that is already known to work in people, just like how flu and polio vaccines were made. This approach allows the vaccine to be manufactured and distributed on a reasonable scale.
But, the drawback is that it requires special laboratory conditions to grow the virus safely. And, it can also have a long-drawn production period, compared to other approaches. Lastly, it requires at least two or three doses to be registered.
- Viral-Vector vaccine
The viral-vector vaccine uses a safe virus approach to deliver specific sub-parts or proteins of the concerned virus so that an immune response can be triggered without causing the disease or infection. To do this safely, the guidelines of developing particular parts of the pathogen considered are inserted into another safe or rather, healthy vaccine.
Now, the safe virus serves as a platform (vector) to deliver the protein into the human body. The protein then triggers the immune response. The pros of the viral-vector vaccine include that it can be developed rapidly. The Ebola virus vaccine used the viral-vector vaccine.
- Live-Attenuated vaccine
Live-attenuated vaccines use a weakened or attenuated (meaning, deactivated) form of the bacterium or virus, or one that is the most similar to it. They use well-established technology, provide strong immunity, and are relatively simple to manufacture. The mumps and rubella (MMR) vaccine, measles, chickenpox vaccine, shingles vaccine, etc., follow the live-attenuated vaccine approach.
2. The Sub-Unit approach
It is seen that rather than injecting an entire pathogen to trigger an immune response (whole-virus or whole-bacterium approach), the sub-unit approach also known as acellular vaccines contains purified parts of it.
These specific parts are selected carefully based on their ability to stimulate immune cells. Considering this approach to be the safest as it’s fragments are incapable of causing diseases and infections as compared to whole-virus vaccines.
There are many types of subunit vaccines: conjugate sub-unit vaccines boost the immune response by binding a polysaccharide chain to a carrier protein, protein subunit vaccines contain isolated proteins from viral and bacterial pathogens, polysaccharide vaccines contain threads of sugar molecules found in the bacterial cell walls.
However, only protein sub-vaccines are being used to develop vaccines that will fight against COVID-19 infection. Besides, other subunit vaccines are in widespread use, including the hepatitis B and MenACWY vaccines.
The advantages of the sub-unit vaccine include well-established technology, they are relatively stable and contain no live components that could cause the infection. They are also suitable for people who have compromised immune systems. The main disadvantage of the subunit vaccine is that they are relatively complex to manufacture.
3. Nucleic Acid Vaccine
The Nucleic Acid Vaccine uses genetic information from the disease-carrying pathogen (virus or bacterium) to try and stimulate an immune response against it. Now, depending on the vaccine, the genetic material used can be either DNA or RNA. In both cases, it provides guidelines on how to make a specific protein from the pathogen which the immune system will be able to identify and recognize as an antigen or foreign body.
Now, once it is inserted into the host cells, the genetic information is read by the cell’s protein-making machinery and then used to produce antigens that trigger the immune response.
It should be noted that this is a relatively new approach to developing vaccines. However, RNA and DNA vaccines are being developed for the COVID-19 vaccine. They have been licensed for animal use, but they haven’t gone through clinical trials on humans yet.
Nucleic acid vaccines are relatively easy to manufacture and thus, there are high hopes regarding the RNA and DNA vaccines.
This is everything you needed to know about the COVID-19 vaccine. When your time comes, don’t hesitate in taking the vaccine, and don’t believe any rumors based on hearsay. For authentic knowledge, only refer to the WHO site or the government-authorized websites.