News from CRIS: Vaccine Safety - Background

January 12, 2021

What are vaccines?

A vaccine is a biological substance called a biological preparation designed to provide our body with active immunity to particular infectious diseases when appropriately administered.

What do vaccines do?

Vaccines stimulate immune memory. Once we've received a vaccine, our body's immune system can recall a specific pathogen's identity, even years later, and effectively fight the pathogen.

How do vaccines work?

When the vaccine enters our body, it contains safe levels of agents, ingredients, and sometimes attenuated (weakened) or inactivated pathogens. The vaccine mimics an infection and activates our immune system to produce specific antibodies that recognize and neutralize or destroy these toxins or pathogens.
More importantly, the vaccine-activated immune system will generate memory immune cells that remember how to combat the pathogen on future exposure. 

So, when we encounter the infectious disease later, our body knows how to effectively react to the pathogens that cause the disease and can quickly destroy the pathogens before they cause serious illness.

It can help to think of vaccines like an army training new recruits. Like training new recruits, vaccines transform our uninitiated white blood cells into experienced soldiers called, “memory” white blood cells. Memory white blood cells have the tools (antibodies) needed to efficiently eliminate invading infectious organisms such as bacteria, viruses, and parasites.

Every day our white blood cells serve as scouts on the lookout for invading organisms. If our scouting white blood cells find such an invader prior to us receiving a vaccination, we’re without a trained army of memory white blood cells to help defend us. Because it takes time for these white blood cells to multiply and expand into an army, it can take a week or weeks to eliminate such an infectious invader before we feel well again. In extreme cases, the invaders can win resulting in death.

However, if we’ve been vaccinated against a specific infectious organism, we will develop a trained army of memory white blood cells armed with the correct weapons (antibodies) to defend our body by destroying the infectious organism before showing symptoms of a disease, or we may exhibit very mild symptoms.  


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