Good afternoon everybody it's Dr Nick Coatworth with today's top three and
the shout out today this weekend goes to everybody around Australia who's
enjoying themselves with restrictions being lifted again across Australia.
States and territories are gradually lifting their restrictions but I want to
let you know that that does not mean that we should change our behaviours.
Restrictions lifting means we can do more, but our behaviours have to stay the
same. And that means that we need to wash our hands frequently, we need to keep our
distance where we can, and we need to download the COVIDSafe app to help the
disease detectives in case we get in contact with or are diagnosed with COVID-19.
And most importantly, as we enter into this winter season, if we are unwell
with respiratory infection, we need to keep our distance from others, stay at
home and get tested. So for today's top three, I wanted to talk about clusters
and outbreaks because that is in our suppression strategy going to be the way
of the future for 2020 and potentially beyond, as we live with COVID-19
without a vaccine or effective treatment.
Our first question today, what is an outbreak?
So that's a good place to start. And an outbreak is a situation where we
have more cases of a disease in a given place or time, that we would normally
expect. So in a situation of very low numbers of COVID-19 across the
Australian community, when we find a case or a couple of cases, we would define
that as an outbreak because that's an increase in what we would normally see.
And what we're expecting to see across most communities is very little
or no COVID-19. So when you get one or two or more cases that becomes an
outbreak. So when does an outbreak become an epidemic? Well an epidemic is
the widespread occurrence of an infectious disease in a community at a
particular time where the disease is not permanent. So we are in a COVID-19
epidemic because we didn't have COVID-19 in 2019. And in fact, we're at more of
an epidemic, we're in a pandemic because we've got global spread of COVID-19
across all continents in the world, so that approaches the definition of a
pandemic. Let me give you a few examples of other disease outbreaks which you'll
be even more familiar with than COVID-19. Well, SARS-1 which occurred in the early
2000s was one of those. It was a multi-country outbreak in 2003 of a
coronavirus, similar to SARS-Coronavirus-1. Listeria is another one that we
commonly hear about and that is a foodborne illness and there was an
outbreak of listeriosis in 2018 in Australia and that was traced back to
rockmelons. You might remember a whole heap of rockmelons got pulled from the
shelves and those rockmelons were actually produced by a single grower and
there were 20 reported cases around Australia. some of which were actually
fatal. Hepatitis A is another good example that people will be very
familiar with because that was the one that was in the frozen berries and I
believe it happened in summer when a lot of us had frozen berries in our freezers
and we had to get rid of them. So they are good examples of diseases
that are not usually within our community and then when they surface we
define them as outbreaks. For COVID-19 in Australia, the main outbreaks are
located in Victoria, where there are a number of small outbreaks associated
with household clusters or hotel quarantine and the key to containing
these outbreaks of course is to detect those cases as soon as possible. We know
when we look at the modelling of any infectious disease spread that the sooner you
detect the case, it's kind of logical the less chance that individual has to
spread that infectious disease to others. So that's why it's so important we keep
banging on about getting tested so quickly and not leaving it for a few
days, because if you get tested and you get diagnosed and
then you get put in quarantine if you're positive, of course.
But that stops disease spreading within the community, I did want to mention
there though, that we do acknowledge the difficulty, particularly those in casual
employment who for whom it would be difficult to take time off. And what I
would say is that the testing around Australia is returning results very
quickly, within one or two days in urban areas, I know that's not the case in
rural and regional areas. But if you have any concerns about that then certainly
ask your GP or when you go to the respiratory clinic, get them to give you
an indication of the test turnaround, that's very important. We can't emphasise
that message enough, we need to continue to get ourselves tested for COVID-19
to help those outbreaks and the disease detectives bring those outbreaks under control.
And our second question for today, what is a cluster?
So is there a difference between an outbreak and a cluster? And there is, the definition
of cluster is slightly different a disease cluster or infection cluster is
a group of similar health events that have occurred in a group of people
living or working in the same area or around the same time. We tend to talk
about clusters in the early phases of the investigation as we try and
ascertain whether things are connected to a particular outbreak. So often, you
see different geographic clusters and the disease detectives are working to
determine whether they're connected or not. For example, if we see a
number of people with a disease in the same suburb, we'd call it a cluster and
we keep an eye out for clusters because that might suggest that there's an
outbreak in that particular area. Sometimes we can't tell exactly where
someone has caught the disease, we can't identify a particular person with the
disease that they had close contact with. But the fact that they live in the same
suburb or work in the same building means that we think the case is probably
related. Now that we're sitting in 2020, we can also use a technique called
genomics, where we actually do the genetic sequence of the virus, and if
there's no difference between the strains or very minimal difference
between the strains of two unconnected people, we can actually join those, a bit
like a genetic dot-to-dot where we can work out that those cases are actually
connected. And that's been very helpful in Australia. Australia has been a world
leader in using genomics as a means of connecting cases.
Our last question for today, are clusters and outbreaks managed differently by health authorities?
Not really because they're part of the same spectrum, they're just a slightly
different definition. The Department of Health works, the federal
Department of Health works with state and territory health authorities to
manage COVID-19 clusters and outbreaks and to bring you the national
picture of what's going on. So individual health authorities and the state and
territory though, they actually take the lead because under the Constitution, so
you know for greater than a century, public health has been the primary
responsibility of the state and territories and why is that sensible?
Well, they obviously know what's happening locally and have a very good
impression of where an outbreak or cluster might be occurring
and whether that might be linked to a particular local outbreak. So it makes
sense that a state and territory focuses on their own public health. So sometimes
we can identify at the source of an outbreak quickly.
For example person A, went to work and five other people caught the virus from
them and took it home to their families. In that case, the state health
authorities work with the workplace itself, the owner of the workplace and
that could be any sort of workplace, it could be the abattoir like Cedar Meats or
it could be a school. as we've seen around the country. And we want to make
sure that's safe and we also might arrange a deep clean. What we would
definitely do as a state health authority, is look around that workplace
within the household contacts of the people who work there and within the
suburb and we look very very closely, so you might see a pop-up clinic, pop-up
testing clinic, you might even see some testing of people without symptoms
to determine who might be carrying COVID-19 without many symptoms at all within
that community. And that's like a cocoon approach where you start in the middle
of the affected our workplace or cluster and then you work out to see how far
it's gone. So while public health authorities work hard to try and
identify where each person caught the disease, it's actually not always
possible. They might see a pattern in the cases, such as more from a certain suburb,
and that might be because there's an outbreak there or might just be a
coincidence. They'll work with the individuals
involved to make sure the virus doesn't spread further and that's where we talk
about quarantine and isolation. They'll work with people who are connections
between people and cases to try and work out that source, and if they can't
they'll work out what extra steps need to be taken in that area, such as some
that I've just described. They might let the community know that there's a higher
number of cases and they will certainly let the community know if they feel that
there needs to be more widespread testing within that community. This is
the sort of pattern that we can expect for the rest of 2020 in Australia. Even
in states and territories that have no cases at the moment, as we've seen in
New Zealand, the systems are not perfect, the border controls are not perfect and
there's only one reality that we have to deal with and that is that we have a
population that is not immune to a respiratory virus. So nationally that
means our strategy can only be suppression and that strategy has been
successful so far, and we're able to open up our economy, we've seen an increase in
the social movement, but by and large the number of cases has remained quite low.
That suppression is helped enormously by you being able to continue those
behaviours of washing our hands, keeping our distance, having our app and making
sure we stay at home when we're unwell and getting tested. I hope you've enjoyed
the message for this weekend, I do sound like a broken record, but we'll keep on,
we'll keep on doing it for 2020.