A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. Vaccination comes from the Latin word “Vacca” meaning cow.

First used to eradicate smallpox estimated to have killed about 300-500 million people.

Vaccination is different from inoculation in that inoculation is a process where the actual pathogen itself is injected and in some cases, the person inoculated may catch the disease and infection can become serious as well.

Variolation: Practised in Ottoman Empire for immunity against smallpox, brought to England by lady Lady Mary Wortley Montagu. Required quarantine. Milk Maids rejected the procedure claiming they had cowpox. 

Immune cells start as stem cells within the bone marrow. Lymph nods store immune cells to be released during pathogen infection and swell during infection as a result.

Antigen Presenting Cells (APC) monitors blood for pathogens and on finding them start the process of Phagocytosis where the pathogens are ingested and broken down to be presented to the nearest lymph nodes which start the immune response. These pieces of pathogens are called antigens.

APC activates the T cells which oversee the cytokine proteins. These proteins of the immune system help regulate immunity. B cells multiply and generate antibodies that can kill the pathogens.

After the first infection, these T and B cells remain in the system preparing for future pathogen invasions.

Two types of vaccines:

Live attenuated vaccines: a mild version of the pathogen is used. Effective for a long time but the risk of being infected.

Inactivated vaccine: Dead pathogens or parts of pathogens are used. It is effective for a short term and repeated booster shots might be essential. Safer.

Herd Immunity: When a majority of people in the society get immunity which slows down the spread.

Immunological memory: Ability of an immune system to quickly and specifically recognise an antigen the body has previously seen and then initiate an immune response.

Acquired Immune System: It is a subsystem of the immune system that consists of specialised cells and processes that eliminate pathogens by limiting their growth.

Vaccination can fail due to difference in immunity amongst people. Usually has side effects and no vaccine is 100% effective

Source:

Infographic Show video: How Are Vaccines Actually Made

Reddit post on Rabies: What's a scary or disturbing fact that would probably keep most people awake at night?

Image by cottonbro from Pexels

See omnystudio.com/listener for privacy information.