It’s sometimes quite hard to look back in history and
find the origins of particular medical procedures.
But there is evidence for the ancient Chinese practice of
variolation using dried smallpox scabs blown into the nose.
This produced a milder
form of the disease.
It was not without risks.
Around about 1-2% of
variolated individuals died.
However this compares with approximately
30% who died following natural infection.
These individuals were subsequently
protected from smallpox.
By 1700, variolation had been adopted
in India, the Ottoman Empire and Africa.
Edward Jenner noted in England that dairymaids
infected with cowpox became immune to smallpox.
In 1796 he deliberately infected a boy, James
Phipps, with cowpox through scratches in the skin.
Subsequently he exposed
the boy to smallpox.
Clearly with today’s ethics committees, there
is no way this experiment could be done.
But in those days he
was able to do this.
And I’m sure he was incredibly relieved to find
that the boy was actually protected.
Jenner published his findings in 1798, concluding
that vaccination provided immunity to smallpox.
And this really laid the foundations of
modern day vaccinology as we know it.
So what’s required for
a successful vaccine?
Of course it needs to be
effective, it needs to work.
It needs to elicit an appropriate adaptive immune
response, that will depend upon the particular pathogen.
Are antibodies required to defeat the pathogen
or are cytotoxic T-lymphocytes required?
Or maybe both?
The vaccine needs to be stable,
needs to be affordable.
So it needs to be
And of course it has to be safe.
There are two infectious diseases that have been completely
eradicated from the world following
global vaccination campaigns.
Smallpox was eradicated from
humans in the year 1979.
Rinderpest which does not affect
humans but is a important disease of
cattle, economically very important,
was eliminated in the year 2011.
These are the only two infectious diseases
that so far have been eliminated by vaccination
but they show that it is possible to eliminate
infectious disease using these procedures.
Polio could well be the next disease
that is eliminated following vaccination.
Here you can see the notifications of
paralytic polio in the United Kingdom.
And you can see that following the
introduction of vaccination in
the mid 1950s, initially with the inactivated polio vaccine IPV.
And then a little bit later, the oral
polio vaccine which is a live vaccine;
that by the mid 1960s, polio was essentially
eliminated from the United Kingdom.
As of March 2016, polio has been eliminated
from the vast majority of the globe.
In fact, it’s only currently endemic
in Afghanistan and Pakistan.
That doesn’t mean that it couldn’t potentially
reestablish itself in other countries.
But at the moment, there’s just a very small
area of the world where polio is still endemic.
And of course the hope is that in the very near
future, it will be completely eliminated and
join smallpox and Rinderpest as being a disease
that has been eliminated by a vaccination.