Everything you need to know about vaccines!!

" Vaccine " , this is one of the most common word we hear nowadays. But do you know the history of the discovery of the vaccines? ...

"Vaccine" , this is one of the most common word we hear nowadays. But do you know the history of the discovery of the vaccines? How does it works? what are it's limitations? or do they have any side-effects? These questions might have strucked you several times. In this post, let's try to figure out the answers, to these type of questions.

What is a vaccine?

Vaccine, in some cases, is a biologically prepared parts of a antigen which is weakened or inactivated in labs. While the newer vaccine only contains the blueprint for producing antigens rather than the antigens itself.

Origin:

The concept of vaccination, i.e, immuning the body to fight a particular antigen by introducing it in the body in a controlled manner; is very old. Since the ancient times, there has been a practice of introducing non-lethal amounts of poison in the body in order to immune one self against the poison. Mithridatism was one such process named after Mithridates VI, the king of Pontus who pioneered this method. In ancient India, Vishakanyas were beautiful girls who were made immune to poisons and anyone who made love with them, would die due to poison in the body.

In the mordern world, Edward jenner is known as the founder of vaccination in the west. In 1796, he inoculated a 8-yrs old using cowpox after which he showed immunity against smallpox. He first infected the boy with cowpox virus after which he felt sick, although after recovering from the virus he showed immunity against small pox. This was like a kickstart in the development of vaccines. The vaccine got it's name from the fact that the cowpox used to infect the child was called "vaccinia" virus.

working:

Step-1:

Our blood contains white blood cells which are responsible for building and maintaining our immune system. They are of various types, few of them are - Monocytes, Lymphocytes, Neutrophils and Macrophages.

Step-2:

 So, as soon as the pathogen(virus or bacteria) are introduced to the body, either naturally or manually through vaccines, they are engulfed by the Macrophage cells. It then breaks the virus infected cells into pieces and projects it's protein samples on the surface(just like carriers).

Step-3:

 After that, T-Lymphocyte cells detect the projected cells, processes it and passes on the information to the T-killer cells and B-lymphocyte.

Step-4:

T-killer cells starts terminating the infected cells to prevent the spread of the virus, whereas B-lymphocyte starts to decode the protein structure and then creates the plasma cells and memory cells.

Step-5:

 Plasma cells contains the specific antibody for the pathogen and starts the mass killing inside the body whereas the memory cells keeps the information of the antibody created so that when our body encounters the same virus or bacteria again, no time is wasted in the previous steps. Step 5 will be executed directly that's why once immune to a pathogen, we don't even fall ill the second time.

But there are some cases where the memory cells don't work well and the immunity is again lost and we need to revoke it using booster doses.

There are mainly two types of antibody:

1. IgM - They have high efficiency, low half life, made instantly and are usually destroyed in few days.
2. IgG - They are more specific and have a greater half life, takes more time to be produced and persists in body for several weeks before getting destroyed.

1st dose of any vaccine usually helps body produce IgM instantly to provide protection and IgG slowly to persist in body and the second dose just produces IgG which in turn provides longer immunity.

What are the different types of vaccine?

There are mainly 5 types of vaccines:

• Live Attenuated vaccine - These vaccine contain the whole virus which have been weakened through the genetic modifications creating a controlled immune response. Since they are closest to the real virus, they provide strong and lasting immune response, but can be hazardous for the person with very weak immunity. That's because weakened bacteria or virus in some cases can multiply too much and can trigger the disease. Vaccines for Measles, Mumps and Chicken pox are few of its example.

• Killed or Inactive vaccine - These are the earliest developed vaccines. They use the strain of the dead virus or bacteria which are killed by either heat or some chemicals. They usually do not provide the long lasting immunity and are not as strong as the live vaccine and may need to be boosted with multiple doses over time. But they are also less hazardous then the live vaccine. Polio and Hepatitis-A are few of it's examples.

• Subunit and Conjugate vaccine - They use the different parts of the bacteria or virus instead of the virus itself. They target the main working point of the virus or bacteria. So they provide very strong immune response and are safe too. Person with weak immunity can also use these type of vaccines. Although it provides strong protection, they may need to be boosted like the killed vaccines. Hepatitis-B and Influenza are few of it's example.

• Toxoid vaccine - These vaccines use the toxins released by the disease causing virus or bacteria. This helps in order to get the focused immunity against the virus. The toxins trigger the immune response but are extremely safe due to the fact that they are not able to replicate because there is no virus, just the toxins. They don't provide long lasting immunity and need to be boosted over time. Diphtheria and Tetanus are few of it's example.

• mRNA and Vector-based vaccine - These are currently in development stage and are the newest one. In the mRNA vaccine, they just direct few of our cells to directly produce the specific protein used by the targeted virus which are finally terminated by our immune system providing us the immunity. And in the Vector-based vaccine use other viruses as a shield to protect us from the targeted virus. These can be produced very cheap and fast but need to be stored under very low temperatures. Pfizer BioNTech and Moderna Covid-19 are few of it's example.

What is the importance of Vaccines?

Inoculation, the process of gaining immunity to a virus or bacteria through vaccination is very old and very important for the human civilization. The advancement in the medical field has lead us to various process and types of vaccination which has improved our standard of living with no doubts. The disease which we feared few decades back are now no threat to us just because we get the vaccines on the right time. As soon as a baby is born, the process of vaccination is initiated. That's because we know the importance of vaccination and it has helped us survive various pandemics.

Like Covid-19, no one knows what kind of pathogens and disease, we are gonna encounter in the future but one thing is for sure, that sooner or later, humans will be able to create the vaccine.

I hope this post was helpful for you and would have given an insight of vaccines, and how it works.