A vaccine is a lab-based product that presents active acquired immunity to a selective infectious disease.
Science Behind Vaccines
Vaccines work by copying disease agents and spurring the immune system to build a defense system against them. In order words, the immune system identifies vaccine agents as alien, destroys them, and “remembers” them. When the destructive version of an agent is met, the body recognizes the protein coat on the virus. Thus, it is ready to respond by first offsetting the target agent before it can penetrate cells, and secondly, by realizing and killing infected cells before that agent can multiply to enormous numbers.
Different kinds of Vaccines
Vaccines contain inactivated, or dead organisms or purified products stemmed from them.
There are different types of vaccines in use. These symbolize different strategies to decrease the risk of illness while maintaining the ability to induce a helpful immune response.
- Inactivated Vaccines: Some vaccines contain inactivated but previously virulent microorganisms that have been dissolved with chemicals, radiation, or heat. Examples include the hepatitis A vaccine, polio vaccine, and rabies vaccine.
- Toxoid Vaccines: Toxoid vaccines are made from inactivated toxic compounds that cause sickness rather than the microorganism. Examples of toxoid-based vaccines include diphtheria and tetanus. Toxoid vaccines are known for their efficiency. Not all toxoids are for humans; for example, Crotalus atrox toxoid is used to vaccinate canines against snake bites.
- Attenuated Vaccines: Some vaccines hold live, attenuated microorganisms. Many of these are actual viruses that have been cultivated under circumstances that disable their destructive properties or use closely similar but less risky organisms to produce a general immune response. Although most attenuated vaccines are viral, some are bacterial. Examples include measles, yellow fever, rubella, and the bacterial disease typhoid.
- Subunit Vaccines: Rather than injecting an inactivated or attenuated microorganism to an immune system (which would constitute a “whole-agent” vaccine), a subunit vaccine uses a part of it to develop an immune response. Examples include the subunit vaccine against the hepatitis B virus.
- Conjugate Vaccines: Certain bacteria have outer coats that are poorly immunogenic. By joining these outer coats to proteins (e.g., toxins), the immune system can be led to understand the polysaccharide as if it were a protein antigen. This method is employed in the Haemophilus influenzae type B vaccine.
- Heterotypic(Jenner’s Vaccine) Vaccines: These are vaccines that are pathogens of other animals that either does not cause infection or cause mild illness in the organism being treated. The perfect example is Jenner’s use of cowpox to defend against smallpox.
- RNA Vaccines: RNA vaccine is a novel type of vaccine made of the nucleic acid RNA, packaged within a vector such as lipid nanoparticles. Several RNA vaccines are under research to combat the COVID-19 pandemic.