coronavirus special
What do we know now about the virus that we didn’t know
three weeks ago?
Viral thoughts
An Australian virologist
on what we know so far
about COVID-19 and what
we should do about it.
Ian Mackay interviewed by Conor Burke
I
an Mackay is an adjunct associate professor at the University
of Queensland and has a PhD in virology. He has been sought
for comment by many news outlets worldwide during the
COVID-19 crisis. This is an edited extract from two conversations
Aged Care Insite had with Mackay during March 2020 about the
novel coronavirus.
We know it can survive in aerosols as an infectious virus, and it
can do that for at least three hours. That doesn’t mean that’s a
major transmission route, but it does mean that it’s a possible
route. We have now some evidence to suggest that could
happen. We also know the virus can survive on surfaces for up to
72 hours, especially shiny, hard surfaces. We assumed that based
on other coronaviruses, but now we have the evidence for this
particular virus.
We now know that when kids are infected they can get a range
of illness, not just mild illness. They can get more moderate and
severe illness as well, but we still don’t know how much they
transmit the virus, which is obviously important to know for
school closures and monitoring.
We know asymptomatic cases can have RNA detected
and for quite some time, and there’s a growing body of
evidence that suggests that they can pass that virus onto other
people and infect them, so it does seem that they can transmit
the virus.
We also know it has caught a lot of asymptomatic transmissions,
a lot more than we probably initially thought, based on some
modelling and some analysis of different outbreaks around the
place. So there’s quite a bit of new stuff.
Do we have a better idea of how many people on average a
single person can infect if they have the virus?
We’re still looking at about 2–4 people, but it does depend on the
situation. One good example is the cruise liner. I think about 20
per cent of the people on that cruise liner were infected. It was
something like 700 out of about 4000. You might have to recheck
my maths. And the death rate there was, I think, seven people out
of about 700, so about 1 per cent.
Now, while that’s not typical of any other situation, it gives us an
idea of what an enclosed group can do before intervention is put
in place to stop the spread. So, we’re looking at maybe 20 per cent
of the population becoming infected. That’s interesting.
ACI: What do we know about COVID-19? We’ve seen comment from ‘experts’ that everyone will get it. Is
that a true statement?
IM: It’s a coronavirus, which is a virus we already have experience
with. There are four that exist and circulate among us, peaking
every winter. It’s mostly a virus in children. We can get reinfected
with them, and they can cause things like the common cold and
sometimes pneumonia. They’re associated with croup and can
affect the elderly as well.
We know that we’re not all going to get infected and ill. We
might get infected, but we may not become ill, and that all still
needs to be teased apart. We know that the people who die are
mostly the elderly and those with some sort of underlying cardiac,
lung or kidney disease.
In that sense, it’s a bit like another coronavirus called MERS, or
Middle East respiratory syndrome. Unlike the SARS coronavirus,
this virus, SARS-CoV-2 [the technical name of the virus that causes
the disease COVID-19], seems to be able to shed when we’re
mildly sick, not just when we’re really sick.
With the original SARS virus, you needed to be quite sick
before you’d see the virus coming out. With this one, you can
be asymptomatic and still have the infectious virus in your upper
respiratory tract. Whether that’s the source of transmission
remains to be proven, but the potential is there. We’re looking at anywhere between maybe three and 80 per cent
of the population being infected. We’re all susceptible because
we don’t have antibodies or any sort of immune cells, as far as
we know, that will protect us from an infection, so we’re all likely
to be infected. It’s just that concept of an infected person walks
into a bar, how many people walk out that are infected? We don’t
know that.
But we do know that it’s likely, certainly in the years to come,
that we’ll all experience an infection at some point, the same
way we’ve all been infected by flu or by other coronaviruses or
rhinoviruses or RSV [respiratory syncytial virus]. Eventually, we get
infected by them.
With these other viruses, though, we mostly get them as kids,
because that’s when we spread all our viruses. However, this one
at the moment is just going to keep moving, because it’s going to
find host after host who is susceptible so it can keep jumping from
person to person.
And yes, we’ll see a big chunk of people infected initially,
and then over time it’ll come back in other waves, because it’s
unlikely that we’ll ever get rid of this virus. So we will all, eventually,
be infected.
18 agedcareinsite.com.au