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Vaccine is a substance which contains either killed or weakened configuration of disease causing agent to provide immunity for that disease. Vaccines help the body to identify threat and can help in creating resistance from the disease and also fight it. The term “Vaccine” is taken from a Latin word “Vaccinus” that means “from cows”. Edward Jenner injected injections of cowpox to provide them immunity from smallpox.
Also read: Difference between Active and Passive Immunity
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Key Terms: Diseases, Immunity, Antibodies, B-cells, Inactivated Vaccine, Toxoid Vaccine, Live Attenuated Vaccines, Subunit Vaccine, m-RNA Vaccine
Vaccine: Definition
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Vaccine is used for building antidotes within the body to provide immunity against one or more diseases. Biologically, it can be defined as a preparation that has been formulated to provide prevention from harmful diseases.
Immune system gets stimulated and once stimulated, cells producing antibodies which are called B-cells (B lymphocytes) remain ready to counter agents which try to enter inside the body. This process of carrying out vaccine is known as vaccination. Vaccines are generally provided for harmful diseases like smallpox, chicken pox and other infectious diseases. First vaccine was developed in 1796.
How Does Vaccine Work?
Classification of Vaccine
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Vaccine is classified based on how active components, antigens used in it produce specific immunization against a particular disease causing organisms are being prepared.
Here is a detailed classification of Vaccines:
- Inactivated Vaccine: This category of vaccines are formulated by inactivating a pathogen by using various chemicals like formalin or formaldehyde, which kills the ability of the pathogens but still keeps it intact in the systems to remember it. These vaccines provide protection against diseases like Hepatitis A, Rabies, Polio, and Flu.
- Toxoid Vaccine: Few diseases are there which are produced by toxins from bacterium. Here, diseases are not directly caused by bacteria. In this case, toxins which cause symptoms of the disease are inactivated by immunizing pathogens. During this process, viruses or disease causing organisms are used to inactivate or kill vaccines. This procedure is done using chemical like formalin or by heat as treatment. Various diseases like diphtheria, tetanus can be protected with this vaccine.
Read about: Human Bacterial Diseases
- Live Attenuated Vaccines: One or two doses of this particular vaccine gives life time protection against the harmful diseases. These vaccines create long-lasting and strong response. This vaccine contains a little amount of virus that is injected in the body. The live-vaccines provide protection against the harmful diseases like Smallpox, Yellow fever, Chicken pox, Rotavirus, Measles, rubella, etc.
- Subunit Vaccine: Specific pieces of germ are formulated in this vaccine to provide a very strong immunity which is targeted by germs. This vaccine can be given to people with weakened immune systems and several health problems. Various diseases which are prevented by this vaccine are Hib, HPV, Shingles, Whooping Cough, Hepatitis B, etc.
- Conjugate Vaccine: Recombinant vaccines are somewhat similar to these vaccines as they are produced with two different elements. Whereas, conjugate vaccines are made from coat of bacteria.
- Valence Vaccine: Vaccine is monovalent that is specially formulated to immunize against a single type of microorganism or antigen. In case of a polyvalent vaccine or multivalent vaccine, protection is provided against two or more viruses.
- m-RNA Vaccine: RNA Vaccine or mRNA Vaccine is a combination of nucleic acid RNA in which a vector such as lipid nano particles are packed in it. This type of vaccine provides various types of benefits in comparison to other vaccines as this vaccine does not have any virus in it. The vaccine provides protection against harmful disease like COVID-19.
- Heterotypic Vaccines: Jennerian vaccine contains pathogens of different animals that cause or do not cause mild diseases by which it is treated.
Why Do we Need Vaccine?
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Vaccine preventss against harmful and infectious diseases like cholera, polio, etc. Injections of vaccines are used to boost immune systems.
Fresh studies and research in Vaccines have helped in protecting from diseases that used to be much more common. For example, tetanus, mumps, measles, diphtheria, pertussis, polio, etc. Many of these infections can cause serious or life-threatening illnesses and may lead to life-long health problems. Because of vaccines, many of these illnesses are now rare.
Immunization
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Immunization is a process in which vaccine is provided to a person to protect from infectious diseases. Immunity that an individual might get from disease is exactly same immunity that is received through vaccine. Immunizations are also known as vaccination, jabs, shots or needles.
The process begins with injection of vaccine in a person’s body and the body develops the required amount of immunity to fight diseases. Antibodies that are injected in the body kills dangerous germs and antibodies stay for a long time inside body to fight germ that may enter body in future. If they still get affected by disease, after vaccination, he or she will suffer with just mild sickness.
Things to Remember
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- Immunization principle works on the common property of ‘memory’ of immune system.
- Injection is given to the patient of snake bites, in which antibodies are injected in patient’s body to fight the venom. This is known as passive immunization.
- Vaccines of disease Hepatitis B are produced from yeast using DNA technology.
- Vaccine was first introduced by a British physician in 1796 named Edward Jenner.
- Small pox was eliminated worldwide through vaccination in 1980.
Sample Questions
Ques. What do you mean by Vaccination? (2 Marks)
Ans. Vaccination is a procedure which involves the weakening or deactivating of harmful disease causes microbes in an individual. It is mainly a drug injected into a person through needles or given orally.
Ques. How is Herd Immunity achieved? (2 Marks)
Ans. When a specific amount of population gets immunity to a particular disease due to the reason that the majority of the people are vaccinated, herd immunity (community immunity) is achieved. Even individuals not vaccinated, like newborns and immunocompromised, get protected to some extent because diseases have less opportunity to spread within community. Vaccines prevent a lot of dangerous and deadly diseases.
Ques. Are vaccines considered safe? (3 Marks)
Ans. Vaccines are tested for years to ensure safety and they do not cause any harm. After several trials and tests the vaccines are approved and are made available for use. Almost all vaccines can cause pain, redness or tenderness at the site of injection.
And some vaccines cause more severe side effects. For example, the original pertussis (whooping cough) vaccine could cause persistent, inconsolable crying, high fever or seizures associated with fever. Although none of these severe symptoms resulted in permanent damage, they could be quite frightening to parents.
Ques. What diseases are protected by RNA vaccines? (3 Marks)
Ans. RNA vaccines are considered to provide protection against:
- Influenza
- Cytomegalovirus Infection
- Rabies
mRNA vaccines have elicited immunity from infectious disease targets in animal models of Zika virus, influenza virus, rabies virus, etc., using lipid-encapsulated or naked types of sequence-optimized mRNA.
Various approaches to mRNA cancer vaccines, such as dendritic cell vaccines and different types of directly injectable mRNA, have been used in several cancer clinical trials. These results showed antigen-specific T cell responses and disease-free survival in certain cases.
Ques. What is cyclosporin A? What is its importance? (2 Marks)
Ans. Cyclosporin A. is an eleven-membered cyclic oligopeptide obtained through fermentative activity of fungus Trichoderma Polysporum. It has anti-inflammatory, antifungal, and immunosuppressive properties. It inhibits activation of T-cells and prevents rejection reactions in organ transplantation.
Cyclosporin A
Ques. Given below is a list of six microorganisms. State their usefulness to humans.
(i) Nucleopolyhedrovirus
(ii) Saccharomyces cerevisiae
(iii) Monascus Purpureus
(iv) Trichoderma polypore
(v) Penicillium Notatum
(vi) Propionibacterium shamanic. (4 Marks) [CBSE Delhi 2016]
Ans. Usefulness of above listed organisms are specified below:
| Name of Micro-organisms | Uses |
|---|---|
| Nucleopolyhedrovirus | Used in biocontrol of insects |
| Saccharomyces cerevisiae | Bread making, Ethanol making |
| Monascus Purpureus | Produces Statin used as blood cholesterol-lowering agent |
| Trichoderma polypore | Preparation of cyclosporin having antifungal, anti-inflammatory, immuno-suppressive properties |
| Penicillium Notatum | Production of antibiotic, Penicillin |
| Propionibacterium shamanic | Preparation of large-holed swiss cheese |
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