If we are managing an outbreak, in general
there are two approaches that we can consider.
Early on, an outbreak or an epidemic or pandemic, there
is slow transmission and maybe the incidence rate is low
In such a time, you can invest
in really good case detection.
Find out who's got it, trace them to figure out
who they gave it to and quarantine everybody.
We call this test, trace and isolate.
TTI - test, trace and isolate.
If you do this well, you can prevent
the disease from getting out of control.
Once it starts spreading rapidly though,
you need to implement mitigation measures
to slow transmission, to flatten the
curve, as we now say very commonly.
And the curve we're talking about is the epidemic
curve that we'll talk about later in this course.
Now many places do both.
In fact it's advisable to do both, especially once
transmission is really quite intense in the community,
you don't want to give up
your TTI, you want to heighten it.
So examples of good TTI that have been used to
really slow transmission of COVID-19 early on,
we see in places like South Korea or
Taiwan or Japan, where good investment
in case detection and contact tracing has
allowed those places to remain mostly open
and not be too adversely affected by the disease.
Those same places still use masks
and distancing which are mitigation effects,
So again, nothing prevents you
from using both of those things.
But be aware that when the disease starts
to transmit really quite intensely at a high rate,
TTI can get overwhelmed and that's when
you need some serious mitigation strategies
to get the incidence rate down
again so that TTI can do its job well.
Again, TTI is testing,
tracing and isolating.
Many countries now add to this an 'S'
for support - test, trace isolate support.
Support refers to the need to economically support the
people who are now being dispossessed by the isolation.
If you're quarantining for weeks on
end, you're not making any money.
You can't feed your family,
you can't pay your rent.
So public health job maybe to help
people that are economically affected by TTI
So test, trace, isolate and maybe, support.
Various infection control strategies we
can implement to mitigate transmission
once TTI is no longer
sufficient to do the job on its own.
Hand washing Of course.
Hand washing is one of the
most potent methods we have
of diminishing transmission of
a number of infectious diseases,
including the flu and the common
cold and possibly COVID-19.
Hand washing should be high up
there in the list of things to advocate
for the general public to do.
It costs nothing and it's easy to do.
Toilet hygiene is important.
Flushing the toilet, cleaning
regularly, not having crowded toilets.
This is particularly important for diseases
that are spread through the fecal route.
COVID-19 is thought to
potentially be spread fecally,
but it's not a major mode of
transmission for the disease.
But toilet hygiene is nonetheless
an important thing to consider
for a variety of other diseases.
Masks and gloves, of course.
When used to protect yourself, we call
them PPE, personal protective equipment,
but masks at the population level aren't
necessarily meant to protect the wearer.
This is an important consideration
and one that's quite confusing for the
general public around pandemic time.
For COVID-19, for example, in nations
that have adopted masks have done so
to mitigate transmission at the population level.
So when high-quality medical grade
masks like the N95 are worn by hospital staff,
they're worn for self protection because
those masks are so dense in their fibrous makeup
that it's difficult for pathogens to cross them.
So you are protected.
For the general public, simple
cloth masks are often sufficient
because the intent is not to
protect the wearer,
it's to slow down the
breath as it leaves the mouth
so that droplets cannot travel more than
a few centimeters past the wearer's mouth.
If you recall, we said that influenza
droplets and probably COVID-19 droplets
tend to fall within 1 or 2 meters.
If you wear a mask, that
comes down to a few centimeters.
That means people can walk in front of you
and have a lesser likelihood of
becoming infected if you are infected.
When scaled up to the population
level, the expectation is that
this diminished probability
of transmission translates
into overall population transmission
decrease and it seems to be working
in many places around the world.
Gloves are useful for fomite protection.
Of course, distancing.
We talk about droplets again.
As I mentioned, studies have suggested that
most droplets fall to the ground within 1 or 2 meters.
That distance increases If you're shouting
or singing or playing a musical instrument,
or a ventilation system is pushing
droplets in a certain direction,
but on average 1 or 2 meters.
That's why many countries have those
thresholds for keeping people away.
You must keep within 1 meter,
1.2 meters, 1.5 meters or 2 meters
depending upon that nation's standards.
So if you're far away from
somebody who's infected,
their droplets will not land on
you and you are probably safe.
Again, none of these
mitigation techniques are perfect,
but they are good and the expectation
is, multiple good mitigation strategies
add up to one very good
overall public health strategy.
And last we of course have quarantine.
So if people are symptomatic,
they are asked to isolate at home.
If we know you are infected,
we will compel you to isolate.
Many nations have quarantine laws
that empower the state to legally imprison,
for lack of a better word, someone in their home
or in a clinic until they recover from the disease
or are no longer infectious.
Thank you very much.