Latin word Variolae vaccinae is the origin of the word vaccine. In 1798 for the first time Edward Jenner developed first vaccine to prevent smallpox. Now vaccine is a biological preparation. It is produced from living organisms. And it will help to induce immunity or sometimes cure the disease. Vaccines can be administered orally or by injection or by nasal routes. Mostly vaccines are in liquid form.

there are types in vaccines

1. LIVE-ATTENUATED VACCINE: In this type, vaccine is prepared using the living microbes which cause the disease. In laboratories a culture of these organisms is grown and the isolated organisms are weakened or disabled. Even though the microbe is alive, it will loose the capacity to cause harm. The organisms can be disabled by culturing them in sub optimal conditions. These are relatively safe and produce strong response and create long memory. But these are very expensive to produce.
2. INACTIVATED VACCINE: Here the disease causing microbe is killed or we can say inactivated through various means. Treating with chemical agents or thermal treatment. These inactivated microbes are purified and formulated into vaccine. This type of vaccine are very safe but the memory created will be comparatively of shorter duration.
3. RECOMBINANT SUB-UNIT VACCINE: Here the microbe is genetically modified and their potential to cause harm is reduced or removed. Some of the components of the microbe can be prepared separately by genetic recombination. Like only a part of protein or DNA can be synthesized and formulated into vaccine.
4. TOXOID VACCINE: If the disease causing microbe is affecting because of the toxic substance that produces, the toxin can be isolated and purified through cultures of the microbe. And then this toxin can be treated chemically so that it will not cause any harm but will be enough to cause the immune reaction in the body. The inactivated toxin is formulated into the vaccine. This type of vaccine is easy to produce and is very safe. But these will also have shorter memory.

what dose a vaccine contains?

The vaccine is not only composed of the antigen in bulk. It contains some additional fluid also. They contain preservatives to have a good shelf life and to ensure sterility and check contamination. These preservatives will not be toxic at the concentration used. The may sometimes have saline or water. Vaccine may also contain adjuvants. An adjuvant is a substance which helps the vaccine to generate stronger immune response. You can say they make vaccines work better. Aluminum salt is a common example for adjuvant.

working of vaccines:

If you get infected, the body will show defense against the foreign substance and immune reaction would have been initiated and the person will get sick. The vaccine is the mimic of the disease causing microbe and will generate immune response without making the person sick. The mimics trigger the antibodies production in the body. Antibodies bind to these mimics and destroy them with the help of immune cells. This helps the immune system to quickly recognize the enemy if they enter again.

Vaccines have great impact on public health. They help to reduce human mortality. They prevent the entire population from the risk of infectious diseases. Many diseases were due to vaccination programs. Polio is an example to that. So everybody should get vaccinated to conquer the pandemic that we are currently facing.