Bacteria, viruses, a parasites that cause disease have the potential to be very dangerous
to humans and animals.
We've gotten better at dealing with disease,
but that hasn't always been the case.
Many diseases have been affecting human populations for thousands of years.
The Black Death, tuberculosis and smallpox
have collectively caused hundreds of millions of deaths.
This is to say, humans have been working on the problem
of infectious diseases for a very long time.
People observed that if you survived an initial smallpox infection,
you would not get sick again.
This led to the development of a technique called inoculation.
It was used to protect against severe illness
for hundreds of years in India, Africa, and China.
Inoculation was the deliberate introduction of material
from smallpox pustules from one person to another.
In some cultures, scabs from people with milder disease
were ground up and blown up the nostril.
Later, skin to skin inoculation was used.
Smallpox caught through the respiratory system often resulted in severe disease.
Infection of the skin usually led to a mild or
localized infection, but still induced immunity to the virus.
The problem with inoculation was that it required a high level of skill
and monitoring of the patients About 1 in 50 people still died,
and new smallpox outbreaks could be triggered by inoculated patients.
It also required a supply of smallpox-infected people
as a source of inoculation material.
Although others were experimenting with using cowpox
to inoculate people against smallpox in the mid 1700s,
Dr. Edward Jenner
was the first one to document and scientifically test his hypothesis.
Could a cowpox infection protect you against a smallpox infection?
In 1796, he inoculated
an eight year old boy with a cowpox lesion from a milkmaid.
The boy had a mild illness, and a few weeks later,
when deliberately exposed to smallpox, he did not develop the disease.
In 1798 Dr. Jenner
published a paper with his results,
having tested this method on 22 other people.
He called the procedure vaccination as a nod to the origin of the inoculation
virus. Vacca is Latin for cow.
Those of you that understand French
might recognize that vache is in vaccine.
By the mid 1800s,
vaccination against smallpox had spread globally
and procedures for producing the vaccine became standardized.
Another famous scientist, Louis Pasteur,
realized that microorganisms cause disease and the spoiling of food.
He discovered that heating wine to 55 degrees
Celsius killed bacteria and stopped it from spoiling.
This is what Pasteur is famous for.
We use this process still: pasteurization.
Pasteur believed vaccines could be found for all infectious diseases.
While studying chicken cholera, he discovered that
exposing the bacteria to air would reduce their virulence.
He named the loss of virulence attenuation.
Injecting chicken with a less virulent strand of bacteria
gave them immunity against freshly cultured cholera bacteria.
He developed vaccines against anthrax and rabies, not realizing that rabies
is caused by a virus. Pasteur's vaccine type is called: live attenuated vaccine.
His work led to the development of vaccine research around the globe
and to the development of vaccines
against many deadly diseases caused by bacteria and viruses.
We now have many different types of vaccines.
The reason for this is because some vaccine types
are not suitable for people who are immunocompromised.
Scientists work to find ways to make vaccine
technology accessible to different populations.
Other reasons for different vaccine types are safety, cost,
adaptability, and time to create the vaccine.
Each type has its advantages and disadvantages, but in every case,
vaccine risks are weighed against the risks associated with disease.
Vaccines approved for use have a low risk of adverse reaction
and the benefits of vaccines
greatly outweigh the risk of complication by natural infection.
Thanks to vaccines
we are better able to combat diseases.
Vaccines are highly effective interventions for preventing
infectious diseases and have great public health importance.
They provide both individual protection and community immunity.
The reduction of disease burden on the population because of childhood
vaccination programs has been phenomenal.
Between 2000 and 2017 vaccines
reduce global deaths by measles by 80%.
The public health measures that have a positive impact on global health.
Number one: safe water.
And number two: vaccines.
This is more impactful than antibiotics.
I cannot emphasize this enough:
this is a cool technology.
Vaccines are safe, effective and save lives.
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