What is VACCINE

 Immunization is the process of becoming immune to or protected against a disease usually by receiving a vaccine vaccines stimulate your immune system to protect you from certain diseases so you won't get sick or get an infection normally the organs and cells of your immune system defends your body from harmful germs such as bacteria and viruses immune cells are constantly circulating through your body they monitor certain substances on the surfaces of cells called antigens healthy cells have different antigens than diseased body cells foreign invaders in the body  immune cells usually ignore the antigens on healthy cells but when immune cells come across antigens on germs they destroy the germ afterward the immune cell displays the germs antigen on its surface this activates other types of immune cells to help get rid of the infection

For example, some activated immune cells 

recognize the antigen on infected body cells and then destroy them other activated immune cells called plasma cells make molecules called antibodies these antibodies travel through your body and lock-on only to germs that have their specific antigen this marks the germ for destruction then other immune cells attack the germs that have these antibodies once the infection is gone some of the immune cells that were exposed to the antigen become memory immune cells in the future if the same type of germ infects your body again the memory immune cells will be ready to destroy it so you don't get sick  this is called natural immunity in many cases it will last your whole lifetime the problem with getting natural immunity from having the disease itself is that some naturally acquired infections can cause serious complications or may even be deadly for example, polio can result in permanent paralysis or death measles can cause swelling of the brain resulting in permanent brain damage or death especially in children under age five and whooping cough is also known as pertussis can cause complications such as pneumonia slowed or stopped breathing and death especially in babies under one year of age.

While symptoms may not be severe in all 

people it's not possible to know who will be affected enough to become  very ill or even die vaccines can protect you from getting these diseases and they are harmful symptomsvaccines often contain a small amount of weakened or killed germs but some contain genetic material such as RNA or DNA that provides instructions for your body's own cells to make the germs antigen usually you receive a vaccine as a shot inside your body the germ particles in the vaccine each your immune  cells to attack these germs this process doesn't make you sick but it does cause your body to make memory cells and antibodies for those germs as a result, if that germ infects your body later in life your immune system is ready to fight the infection so that you don't get sick the main types of vaccines include live attenuated vaccines inactivated vaccines toxoid vaccines subunit and conjugate 

vaccines 

mRNA vaccines and viral vector vaccines live attenuated vaccines use live but weakened germs they're almost like a natural infection and provide a strong disease immunity.

Examples are the measles mumps rubella 

chickenpox and flu nasal spray vaccines inactivated vaccines use inactive or killed germs you may need several doses or booster shots over time examples are there hepatitis flu polio and rabies vaccines toxoid vaccines protect against harmful substances made by germs called toxins they use weakened versions of the toxins called toxoids you may need booster shots to maintain protection against diseases examples are diphtheria and tetanus pDTaP of the DTaP vaccine subunit and conjugate vaccines use only a specific part of a germ they provide strong immunity to that key part of the germ these vaccines may also require booster shots.

Examples are the pertussis part of the 

DTaP vaccine and the hepatitis b vaccine instead of using germs or toxins mRNA vaccines contain a special type of RNA called messenger RNA or mRNA instructs your cells to make the germs antigen 

which triggers an immune response these 

vaccines do not carry live virus and do not change your DNA examples are certain covid19 vaccines viral vector vaccines may use either DNA or mRNA to provide cells with instructions to make a germs antigen the genetic material is wrapped in a different safe virus to take the instructions into your cells these vaccines do not change your DNA examples are certain covid19 vaccines it's important to know that vaccines not only protect you but your community as well many diseases that vaccines prevent are spread from person to person when only a few people in your community are vaccinated the risk of a disease outbreak is high but if most people are vaccinated it's much less likely for a disease to spread this is called community or herd immunity herd immunity is especially important to protect people who can't be vaccinated this includes people with weakened immune systems serious allergies or other health conditions vaccines protect you your family and your community from diseases that can be dangerous or even deadly to find out more about vaccines talk to your health care provider