- Unless you've been
stranded on a desert island,
such as happened to the guy in New Zealand
on the south island,
he's been walking one of
the famous coastal trails.
So he's been two months on his own
and when he went in, COVID didn't exist
and when he came out,
COVID-19 had basically
shut New Zealand down.
So he was supposed to be getting
on a flight but New Zealand
was isolated from the rest
of the world.
So COVID-19 is a very nasty little virus.
It's wreaked havoc throughout the world
and it's wreaked havoc
in the United States.
COVID virus-type epidemics
occur reasonably frequently.
Probably about every 10 to 20 years.
They're not as atypical as people
would like to think they are.
It's just it's been almost 100 years
since we had the 1918 flu,
which got to this level of deaths
in some parts of the world.
In 1927, McCormack invented a mathematics
for studying epidemics.
He developed a set of equations,
which basically took a population,
which was uninfected and susceptible
and worked out how to determine
how many people were likely to be infected
at an particular time.
And also, how long would it take
before the population got to the point
where they had herd immunity.
So even if you've got 100%
susceptible population,
you're not gonna kill all of them
because they're all not
going to become infected.
It's the chances of you interacting
with someone else who is infected
and then you get it
and then those chances change with time.
So when the first
infected person comes in,
there's an entire population
and soon as he runs into a person,
they become infected,
so now you've got two infected people.
And so it becomes the law
of diminishing returns.
Once you get to about
70% of the population,
you're starting to get to
the level of herd immunity.
You're going to have a falling off
in the number of people
who are going to continue to be infected
and the number of people
who are going to die.
McCormack, in 1927,
developed these formula
and they've been used pretty
consistently since that time.
They have made some minor changes to it
but not major changes.
They introduced some new categories,
so we have the category
of susceptible people.
That's someone who hasn't
been exposed to the virus.
Of course, we have the problem
that there will be some people
in that group who have
a natural immunity to it
just because of some other random event.
And so even if we have an entire
population that's exposed,
they're not all going to die.
This is essentially how
particular sets of genes spread
through the population.
We have an exposed population.
Something comes in and triggers a death
and the gene that saves
them becomes dominant
within the population.
We see that with the
introduction of the gene
which looks after the
ability to drink milk
and digest cow's milk.
The difficulty with the COVID virus
with our ability
to collect very fine
statistics very quickly
is we now have a daily death toll.
The only problem with the daily death toll
for the COVID virus is
that we have someone die.
We need to know what day
they actually died on.
Did they die on a Sunday
or is it four or five days
before the death is reported
and put into the statistical system?
So in the beginning, COVID
virus wasn't recognized
as something that was killing people.
It took a while for the
death statistics to catch up
but now we have a reasonably good set
of death statistics going
along on a daily basis.
Once you get a daily set of data,
we then move into a
different set of mathematics.
We can start to look at the
variations in the daily pattern.
The assumption was that there's
no pattern underlying this.
That the overarching ordinary
differential equation
basically gave us a smooth curve
and we just had random
noise on top of that.
Well, analysis using
Fast Fourier Transforms,
which break that noise
into its patterns means
that we can now look
at that daily pattern.
And so we now know
that there is a weekly
pattern in the deaths.
Deaths are lower at a time
when humans are resting
and relaxing like at weekends
in the Western world.
In other parts of the world
where this occurs on Thursday
and Fridays, the same thing happens.
So we now see that there
is a pattern to this
and the pattern is really quite dominant
and we're seeing it in the Untied States.
So this pattern is going
to become something
which needs to be included
in future COVID modeling.
