Vaccination is designed to protect people
against infectious diseases caused by bacteria or viruses
by preparing the body’s natural defenses
to fight specific pathogens.
Vaccines contain either:
• dead (inactivated) bacteria
• viruses
• or components of bacteria or viruses;
however there are also variants with attenuated pathogens
that can still reproduce
but do not cause illness.
Substances are added to them
that place the immune system on alert
to boost their effectiveness.
When vaccinated
the body’s immune cells develop defense cells such as antibodies
to fight the pathogen.
Importantly, it creates a kind of “memory”.
When a real infection occurs,
the immune system recognizes the pathogen.
This means the defense cells
can neutralize the harmful intruders quickly and effectively
to stop the illness before it starts.
This is referred to as immunity.
Depending on the vaccine it may take time
for immunity to develop.
There are also certain vaccines
that have to be administered more than once
at specific intervals
to achieve complete immunity.
Some vaccinations provide lifelong protection
whilst others need to be repeated every few years.
In short:
Vaccination gives the body immunity
to an infectious disease
by mimicking an infection.
The immune system builds up a “memory” of the pathogen.
This allows it to respond to genuine pathogens later on
and stop the disease.