Vaccination and Immunisation: Do you know how we are fighting the current pandemic situation? By staying at home, using masks and sanitisers has helped reduce the spread of the disease, but these are not the permanent solution to get rid of the disease once and for all. We needed a better and more effective solution which is vaccination and immunisation! Taking vaccines and making our body immunised against the virus is the most effective way to fight disease for longer terms.

Vaccination and immunisation are two terms that are often confused together which are not exactly the same. In this article, we are going to learn about vaccination and immunisation, types of immunity and vaccines,  etc. We will also know the history of vaccines and why it is important for us.

What are Vaccination and Immunisation?

As said earlier, vaccination and immunisation are not the same concepts. Vaccination can be defined as a process of introducing vaccines in the human body in order to produce immunity to a specific disease. In simple words, it is the term used for getting a vaccine. Vaccines can be taken as an injection or as an oral dose.

Immunisation is the process of getting the vaccines and becoming immune to the diseases after vaccination. In simple words, immunisation is a process by which an individual becomes protected from diseases.

Fig: Vaccination

Difference between Vaccination and Immunisation

As explained earlier, there are certain differences between vaccination and immunisation. Some of these differences are mentioned below:

Vaccination	Immunisation
It is a process of introducing vaccines in order to produce immunity to a specific disease.	It is a process of getting vaccines and becoming immune to diseases after vaccination.
Vaccines are generally introduced in the human body through injection or through an oral dose. In some cases, it may also be sprayed in the nose.	Immunisation is the body’s natural way to fight against disease by activation of the immune system through vaccination.
If a mutation occurs in disease-causing microbes, then it can render any vaccine ineffective. That is the reason why there is no vaccine for the common cold.	The mutations caused in the genetic makeup of microbes can have a negative impact on an individual’s immune response to diseases.

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Immunity

The human body is an astonishing machine. It has the capacity to repair itself, to battle the assaulting microorganisms, and much more. This self-preparedness of the human body against invasion by microbes is called immunity. Through vaccination, we artificially stimulate our adaptive immunity. Adaptive immunity can be classified as either active or passive.

1. Active Immunity: It is the process of exposing the human body to antigens and generating an adaptive active immunity response. This response may take days or weeks to develop, but it is lifelong. Active immunity is again classified as natural and acquired. If a person gets infected with Hepatitis A virus (HAV) and gets recovered naturally, then that person has developed Natural Active Immunity. On the other hand, if another person gets two doses of Hepatitis A vaccine, then they will develop Acquired or Artificial Active Immunity.

2. Passive Immunity: It is the process of providing IgG antibodies to protect an individual against infections. It gives immediate but short-lived protection for up to several weeks to 3-4 months at most. Passive immunity is again classified as natural and acquired or artificial. The transfer of maternal antibodies (mainly IgG) to the newborn baby through the placenta is an example of Natural Passive Immunity. These antibodies provide passive immunity to newborns for up to several weeks and months until these antibodies are degraded and lost. On the other hand, the process of obtaining serum from immune individuals, and injecting it to protect a susceptible person develops Acquired Passive Immunity.

Fig: Types of Immunity

Herd Immunity: It is also known as population immunity. It occurs when a large portion of a community (herd) becomes immune to a particular disease. Thus, the risk of spreading disease from person to person decreases. As a result, the whole community is protected against that disease. Herd immunity can be achieved in two ways, natural infection, and vaccination. This immunity works only for the diseases transmitted between people and not for the diseases caught from animals and other sources.

Fig: Herd Immunity

The History of Vaccination

1. The first attempt to prevent the disease from disease-causing organisms was reported in the 7th century in India, where Buddhist monks drank snake venom to prevent themselves from serious harm or to develop immunity against snake bites.

2. In 1798, Edward Jenner published the results of his experiments on vaccination in England. He practiced the inoculation of the cowpox virus (Variolae vaccinae), to prevent smallpox in humans. The term vaccine was derived from the term Vaccinae.

3. At the end of the 18th century, Louis Pasteur demonstrated that the harmful nature of disease-causing microbes could be weakened or attenuated in the laboratory. In 1885, he first demonstrated the effectiveness of vaccines against chicken cholera and anthrax in animals before developing his vaccine against rabies for use in humans.

4. By the end of the 20th century, several new methods of producing vaccines such as recombinant organisms, conjugation of polysaccharides to carrier proteins, and the assembly of virus-like particles were developed.

What are Vaccines?

Vaccines save millions of lives every year around the globe. The word ‘vaccine’ came from the Latin word Variolae vaccinae (cowpox), demonstrated by Edward Jenner in 1798. Vaccines are biological substances made of attenuated or killed pathogens injected into the body to stimulate its defence mechanisms against infection or disease.

Vaccines can be administered either by injection, oral, or intranasal routes. Vaccines are made of either the entire disease-causing microorganism or some of its components. Let us learn about different types of vaccines

Fig: Vaccine

Types of Vaccines

Edward Jenner developed the first human vaccine for smallpox. This vaccine was produced by using weak or attenuated viruses of cowpox. Vaccines are made using different processes. They can be made using life attenuated or weakened disease-causing microbes, inactivated or killed organisms, inactivated toxins, or merely segments of the pathogen. Following are five main types of vaccines that are used:

1. Live Attenuated Vaccines: Live attenuated vaccines expose an individual to weak and vulnerable pathogen strain to establish a subclinical infection that activates the adaptive immune defences. Pathogens are attenuated to reduce their virulence using various methods like genetic manipulation or long-term culturing in an unnatural host or environment. Live attenuated vaccines stimulate a more extensive immune response than other vaccines by establishing an active infection. It activates both cellular and humoral immunity and promotes memory for long-lasting immunity.

2. Inactivated Vaccines: Inactivated vaccines are the ones that contain whole pathogens. Here, pathogens are killed or inactivated with various inactivation processes using heat, chemicals, or radiation. The inactivation process must not affect the structure of key antigens on the pathogen for this type of vaccine to be effective. Since the pathogen is killed or inactive, inactivated vaccines do not produce an active infection resulting in a weaker and less comprehensive immune response than a live attenuated vaccine.

3. Subunit Vaccines: Subunit vaccines only expose the patient to the key antigens, not whole cells or microorganisms. These vaccines are produced either by chemically degrading a pathogen and isolating its key antigens or by producing the antigens through genetic engineering. The risk of side effects using these vaccines is relatively low as these vaccines contain only the essential antigens of a pathogen.

4. Toxoid Vaccines: Similar to subunit vaccines, toxoid vaccines do not introduce a whole pathogen to the patient. These contain inactivated bacterial toxins called toxoids. These vaccines are used to prevent diseases in which bacterial toxins play a key role in infection.

5. Conjugate Vaccines: A conjugate vaccine is a form of subunit vaccine which consists of a protein conjugated to a capsule polysaccharide. Conjugate vaccines are developed to increase the efficacy of subunit vaccines against pathogens with protective polysaccharide capsules. These capsules help them evade phagocytosis and cause invasive infections that lead to meningitis and other dangerous conditions. The conjugated vaccine stimulates the production of antibodies against both the protein and the capsule polysaccharide.

6. Nucleic acid Vaccines: Nucleic acid vaccines are a new approach to immunization and immunotherapy in which one or more genes encoding the pathogen’s proteins are delivered instead of living or inactivated organisms or a subunit. A DNA vaccine is designed by incorporating genes for antigens into a recombinant plasmid vaccine.

The aims of these vaccines are to generate immunity against diseases for which traditional vaccines and treatments are not enough. Although most of these vaccines are still in development for humans, they will likely become more prevalent shortly as researchers are working on engineering DNA vaccines that will activate adaptive immunity against many pathogens at once.

Fig: Types of Vaccines

Examples of Vaccines

There are several vaccines produced for different types of diseases. Following are the types of vaccines and their examples:

Types of Vaccine	Examples
Inactivated	Polio, Influenza, Hepatitis A, Pneumococcal polysaccharides
Live-attenuated	Mumps, Rubella, Measles, Varicella zoster
Recombinant subunit	Hepatitis B
Toxoid	Diphtheria, Tetanus
Conjugate polysaccharide-protein	Meningococcal, Pneumococcal, Haemophilus influenzae type b (Hib)

How does Immunisation Work?

Immunisation is the process of getting vaccines and becoming immune to the diseases after vaccination. In simple words, immunisation is a process by which an individual becomes protected from a specific disease.

When we get a vaccine, it stimulates our immune system to produce antibodies that fight and kill the virus. Our immune system has special ‘memory’ cells that remember and recognise specific germs or viruses. Later, when the body comes into contact with the same virus again, it is prepared to fight it. It recognises the virus and immediately produces the required antibodies to destroy it.
The process of immunisation has helped to eradicate many dangerous diseases around the globe. For example, the eradication of polio in India is one of the major milestones achieved by regular polio vaccination campaigns in all the states.

Importance of Vaccination and Immunisation

Immunisation saves not just one but many lives. It protects a person, his family, and also his community. Following are some points that help to understand the importance of Vaccination and immunisation.

1. Immunisation helps in the eradication of diseases and protects future generations. It is one of the best options to protect ourselves, our families, and future generations from a wide range of infectious diseases.

2. In simple words, if a person vaccinates, they help wipe out the disease that could spread now or into the future.

3. It also protects other people in the society who can’t get a vaccine, such as young children, older adults, or the person who is sick or weak.

4. When a particular area is immunized against a contagious disease, most community members are protected against the conditions as the chances for an outbreak or spread are minimized.

5. Vaccination protects children from serious illness and complications of diseases such as amputation of an arm or leg, paralysis of limbs, hearing loss, convulsions, brain damage, and death.

6. The cost of getting immunized is less than getting treated for the diseases that the shots protect.

7. The principle of immunity by vaccination has helped to control various contagious diseases such as rabies, mumps, influenza, measles, and pneumococcal disease.

Summary

Vaccination and immunisation are the most effective strategies for disease prevention. Vaccination is a type of artificial immunity. It can be defined as the art of introducing vaccines in the human body in order to produce immunity to a specific disease. It is a method of artificially stimulating adaptive immune defences. A vaccine triggers memory cell production in the body similar to that of a primary response. Immunisation is the process of inducing specific vaccines and becoming immune to the diseases after vaccination. Artificial active immunity is the basic foundation for vaccination and its development. Vaccination programs not only give artificial immunity to individuals but also nurture herd immunity in cultures.

Our body has the capacity to repair itself, to battle the assaulting microorganisms. This self-preparedness of the human body against invasion by microbes is called immunity. Vaccines are biological substances that are designed to protect humans from infections and diseases caused by bacteria and viruses. Vaccines can be produced by using live attenuated or weakened diseases causing microbes, inactivated or killed organisms, or inactivated toxins, or merely segments of the pathogen.

Frequently Asked Questions (FAQs) on Vaccination and Immunisation

Q.1. What is Vaccination?
Ans: Vaccination is defined as a process of introducing vaccines in the human body to produce immunity to a specific disease. It is a term of getting a vaccine that can be an injection or an oral dose.

Q.2. What is immunisation?
Ans: Immunisationis the process of getting the vaccines and becoming immune to the diseases after vaccination. In simple words, immunisation is a process by which an individual becomes protected from diseases.

Q.3. What are toxoids?
Ans:  Some diseases are caused not by bacteria themselves but by the toxins produced by bacteria. These inactivated toxins can act like vaccines by providing protection against these toxin-induced diseases. Such vaccines are known as toxoids.

Q.4. How does immunisation work?
Ans: When we get a vaccine, it stimulates our immune system to produce antibodies that fight and kill the microbe. Our immune system has special ‘memory’ cells that remember and recognise specific antigens. After that, if we come into contact with this antigen again, our body will be prepared to fight it.

Q.5. What do you mean by vaccines?
Ans: Vaccines are biological substances that are designed to protect humans from infections and diseases caused by bacteria and viruses. It can be administered in liquid form, either by injection, oral, or intranasal routes.

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We hope this article on Vaccination and Immunisation helps you in your preparation. Do drop in your queries in the comments section if you get stuck and we will get back to you at the earliest.