Graphical representation of coronavirus spread in different countries
Florence, Mar 9, 2020
A
very good graphical representation of what I was trying to convey in
words in my previous post. This is what it looks like when the
epidemiological curves of different countries are aligned in time.
First note the acceleration of the spread in all these curves (it's getting steeper and steeper with time).
Note also that there are some differences between the curves. It's
probably too early to speculate about the underlying reasons but
influencing factors could include variances in
- Demographics (e.g. more or less elder people)
- Population density, connectivity within the population (typical housing situation, average social life etc.)
- Number of tests administered (Accuracy of the data)
- Resources and efficiency within the health system
- Time to prepare for the epidemic (!)
- Measures taken and their effectiveness (!)
The
countries where the virus arrived later had more time to prepare. And
for them the future course of the curve is still to be decided. So
let's not waste this opportunity. Taking and adhering to measures that
prevent the spread can make all the difference!!!
A 5-min read that hopefully can save some lives. Please share!
Florence, Mar 5, 2020
Short summary: Please
all remain calm. No need to worry too much. But also: Please worry just
enough so that you take all the necessary precautions against the
coronavirus. If you are not overly concerned for yourself because
you're young and healthy, that's good. However, please do not forget
those with pre-existing conditions, the sick and the elderly, since
they are the ones that are most at risk. This includes some children
but maybe also your parents or your grandparents. For them the extra
years that they may or may not get to live make all the difference in
the world. The following post on the coronavirus and its spread was written from the perspective of someone living in Florence, Italy, on March 5, 2020.
However, given the current situation and outlook everywhere many of the
underlying ideas should be quite generalisable to other places and
times. I just posted this on the local Facebook page “Foreigners in
Florence”, mostly in reply to local people (understandably) urging
people to not give up on visiting Italy (in particular Tuscany): As
a scientist with some knowledge about the spread of epidemics I would
like to offer some explanations and thoughts about the current
situation regarding the Coronavirus. In particular I would like to
explain the reasoning behind some of the measures being taken right now
and even more to encourage everyone to follow them as much as possible. In order to bring my points across I need to be a bit alarmist now and then but I really think this is necessary (“better safe than sorry”).
I tried to be as understandable as possible, but if you have questions
or comments I would be happy to either address them myself (if I can)
or refer you to someone who can (a website or a person). Also please
feel free to share this. I would be even happier if someone could
translate this to Italian. I do speak the language but it would be much
clearer if a native speaker could do the translation. The more people
start to act the better for all of us. Epidemics tend to spread exponentially and this is currently true for the coronavirus
as well. What this means is that for now every person who has the
coronavirus infects on average between 2 and 3 other persons. The
current best estimate for this number is 2.2 but for simplicity let’s
assume it is 2. This means the first sick person in Italy infected 2
persons, these 2 infected 4, those 8, then 16 and so on. One
can see where this leads, both the number of new cases and the overall
number of cases increase with bigger and bigger jumps, so there is not
only further and further spread but the spread actually accelerates.
That’s exactly what is happening now all over the world. For example,
it took Italy about two weeks to go from the first case to 1500 cases
but it took just three days to go from 1500 cases to 3000 cases.
For now unfortunately this acceleration will continue. We are clearly on the rising part of the curve (“it will first get worse before it will get better”).
In order for the epidemic to die out as quickly as possible we need to
press this number mentioned above from 2.2 to below one (which would
mean that over time both the number of new cases and the overall number
of cases would fade away). There
are various ways to do that, for example large-scale vaccination. This
would decrease the number of susceptible people in the population until
at some point the virus can’t find any new hosts and slowly fades away.
Unfortunately, current estimates expect the availability of a
corona-vaccine to be about a year away (first the development itself,
then many tests for side effects etc.). So the next best thing and at the moment our only viable solution is to slow down the spread.
For this people need to finally take the epidemic seriously and behave
accordingly (i.e. follow medical and governmental advice, avoid large
crowds, wash hands etc., basically do everything possible to prevent a
further spread of the virus). The earlier and the more we do that, the
less likely are new infections, and the faster we reach that magic
number of less than 1 new infection for each existing infection. What
makes the whole situation slightly worse is that the numbers we hear
are the number of identified cases and for this there are two things to
consider: the quite long incubation period
(there is a delay of about 5 but up to 14 days from getting the disease
to showing first symptoms) and the fact that even after the incubation
period 80% of cases are quite mild. Both of this implies that a lot of
sick people are not getting tested and thus do not show up in the
statistics.
So
at each point in time there are many more unidentified than identified
cases in the population. For the current situation this means that
unfortunately there are already a large number of infected people
walking around Tuscany and inadvertently spreading the virus. This
again should emphasise the urgency of the situation. So please start to
act now and do not wait until we reach the numbers of Lombardy and
other similarly affected regions. The only difference between them and
us is that the virus got there earlier than here.
As
mentioned above, the often repeated argument that for about 80% of
cases the Coronavirus is basically like a regular flu is true. But
there are two replies to this: First, for the other 20%
it is not like the common flu at all and unfortunately it can get
really bad. And, second and more importantly: if you're young and
healthy and do not have a lot to fear, good for you! But please have
the basic human decency to consider also the fate of those not as
fortunate as you, in particular people with pre-existing conditions
(and this can include children)
and the sick and the elderly who are most at risk. For them the extra
years that they might or might not enjoy make all the difference in the
world. So maybe think of your parents and grandparents first. Even
if the epidemic can not be stopped anymore (and indeed for Italy, and
probably the planet as a whole, this point seems to have passed)
slowing it down is absolutely essential because it means more time for
the health services to react and thus better chances of appropriate
treatment for everyone that will be affected. So again, the earlier
people react the better.
In
this worst case of a largely undiminished spreading what should happen
eventually is that more and more people will get the virus at some
point or another and either recover (the vast majority of us) or pass
away (about 0.5-2% *).
In
the positive case that recovery would provide immunity (which
unfortunately for Corona can not yet be confirmed) this would actually
be very similar to the vaccination scenario described above. In fact,
vaccinations are nothing else than deliberate inductions of very mild
cases of the disease. But the difference to the vaccination scenario
would of course be that in this worst case many people would have died,
so we should really try to do everything in our power to not let it
come to that. A
lot of us are in some way negatively affected by this epidemics. The
sudden drop in people visiting Tuscany has devastating consequences
since many jobs and incomes depend on tourism. This is obviously very
unfortunate and we should do everything possible to alleviate the
situation.
But
as I try to explain in this post, the solution should not be just to
ignore what is happening around us with the virus and to insist on
going on as before. For sure we are already at the point where any unnecessary travel should be discouraged. It just contributes to a faster spreading of the virus.
So instead, better try to find other ways to help each other:
Support businesses in Florence and Tuscany in general (in particular
buy locally, don’t use Amazon), look out for people in need. If you
want to go even further, please spend a week in a nice spa hotel in
Florence or visit an agriturismo in the beautiful countryside nearby,
hire a local guide etc., in short try to replace the missing tourists
from far away.
If
everyone everywhere would do that, we would have more winners or at
least not that many losers from this situation and without any of the
grave consequences of excessive travel. If the worst happens, seek
help, self-isolate or help people that self-isolate (someone healthy
needs to do their shopping etc.). Currently
Tuscany is about two weeks behind Lombardy on the curve. This statement
actually means that inviting people to come to Tuscany in two weeks is
the same as sending them to Lombardy now. Would one really want to do
that?
Or
think about China. What is happening there right now could also happen
here in the future (hopefully not but how can we be sure?). In fact,
the relative numbers of cases are already higher in Italy (Italy 6.4
cases, China 5.6 cases per 100.000 people **).
But
since now we’re talking about the future, it’s still in our hands. The
one thing to prevent us from reaching the high numbers of Lombardy
pretty soon (or of China in the more distant future) is to start acting
now so that the epidemic curve in Tuscany has a milder (less steep)
course than those ones. We actually have the advantage that we have
been warned, so we should not ignore these warnings. Finally,
I would like to stress that there's no need to panic (and in particular
don’t take this text as an appeal to buy masks, deplete supermarkets or
act in a xenophobic manner towards anyone). Life goes on and hopefully
people still can enjoy many of its brighter sides
(https://www.youtube.com/watch?v=jHPOzQzk9Qo).
However, it's completely reasonable to worry and take precautions.
Extraordinary situations require extraordinary measures, at least
temporarily. The point about closing the schools (which seems to anger
many of my friends and colleagues) is that the risk of children
bringing the virus home from school is right now just getting so big
that we shouldn't take that risk anymore.
The
children would almost certainly be fine but they would endanger their
older relatives. That would be especially true here in Italy
(particularly the south) where many grandparents live in the same
household as their grandchildren.
In
epidemics like this one, instead of doing nothing it is certainly
better to prepare for the worst and be pleasantly surprised if things
turn out better. And there certainly is still hope for some more optimistic outcomes.
But it really depends on how each of us deals with the situation. The
earlier and the better we react now, the sooner we can all get back to
normal. * According to current estimates the mortality rate
is about 2% for all but around 15% for people 80 and older (both
numbers should decrease considerably when also more mild cases are
taken into account, current estimates for the final number are close to
0.5%).
**
Italy: 6.4 cases per 100.000 people (as of
March 5: 3858 / 60.4 million)
China: 5.6 cases per 100.000 people (as of March
5: 80430 / 1.435 billion)
This
is where I tracked the number of cases in Italy, where I got the “80%
of all cases are mild” number, the estimate for the incubation period
and also the mortality estimate of 2% (for comparison, for the common
flu this value is 1.3). The estimate for the expected final value of
0.5% is from a calculation of Prof. Craig Feyed, a well-known
epidemiologist who used the “Diamond Princess” cruise ship in Japan as
starting point. https://www.livescience.com/coronavirus-myths.html This is where I found the number 2.2 for the estimated number of new infections per infected person. https://simple.wikipedia.org/wiki/SIR_model This
is an understandable description of a basic epidemiological model. The
green curve in the graph shows a typical behaviour for the number of
infections in an epidemic in which catching the disease and recovering
provides immunity. As mentioned above it is not yet clear if this is
the case for Corona (also for the flu immunity only lasts a certain
time and then you can catch it again). So no one can know exactly how
the Corona curve will develop in the future but it is probably safe to
say that currently we are still rather at the beginning of the rising
part. Three disclaimers:
1. I am not a medical doctor so I cannot give any medical advice, please look elsewhere for this, for example here:
In
case of (suspected) infection, of course better speak to a doctor as
soon as possible (preferably first by telephone, do not just go to the
hospital). 2.
The whole text is written after quite extensive research and to the
best of my (current) knowledge. But please refer to official sites for
more in-depth knowledge and the latest updates. 3.
I’m aware that this is a controversial debate and many people speak
about hysterics, fear-mongering and spreading panic but this should not
prevent us from a reasonable discussion based on facts and careful
extrapolations. If someone has evidence-based counter-arguments to some
of my thoughts I am very open to listen and would potentially
acknowledge that you have convinced me of a different point of view.
Then this would be my new recommendation based on my then best
knowledge. This is how science works, recommendations get updated based
on new data and information coming in.
