Key words
COVID-19 - Coronavirus - Contact Restrictions
Schlüsselwörter
COVID-19 - Coronavirus - Kontaktbeschränkungen
Introduction
In many parts of the world, Germany is seen as a model and exemplary country in the
fight against the new cornavirus. Compared to the rest of the world, Germany has one
of the lowest case fatality rates and handles the coronavirus crisis very well [2]. Germany also seems to have got the
infection rate under control relatively quickly. According to estimates by the
Robert Koch Institute, the effective basic reproductive number dropped below the
critical mark just a few weeks after the outbreak of the disease [6]. In addition to the good German health care
system, the massive political crackdown of social life is held responsible for the
rapid success in disease control. In order to stop the spread of the coronavirus,
German politics has largely shut down large parts of public and cultural life.
Schools and daycare centers were closed, companies were asked to send their
employees home, and extensive contact restrictions were put in place – in
short: public life was torn out of normality and, wherever possible, put into an
artificial deep sleep.
However, from an economic point of view, the consequences of the social lockdown are
gigantic and cannot be compared to any other crisis in the post-war period.
Economists recently predicted a drop in German gross domestic product up to
10% this year [3]. In the end, the
social lockdown will most likely rob many people of their economic existence and
drive many companies into bankruptcy. Against this background, voices were rasied
early, just like in other countries that pursue a strategy similar to Germany, which
called for a rapid end to the drastic measures or even questioned the usefulness of
the contact restriction strategy as a whole. Thus, given the current situation, it
is important to know how effectively the lockdown actually helps to contain the
epidemic.
Based on this question, I will show that the contact restriction strategy has
fundamentally not missed its target. Even if many people question the success of the
strategy, social distancing has actually led to a massive reduction in the infection
rate and thus made it possible to flatten the infection curve. According to the
results of my estimate, the infection rate in Germany would be many times higher
without contact restrictions. The temporary lockdown of social life was therefore an
important and correct step to contain the disease.
Methods
In this study, I look at the daily infection rate in Germany and, based on a set of
plausible basic reproduction numbers, estimate how the infection rate would have
developed had the social lockdown not occurred. I therefore estimate a
counterfactual scenario based on the actual infection dynamics that could be
observed in the first weeks before the first political interventions.
For the calibration of the estimate I use the number of cases documented by the
Robert Koch Institute, an independent German federal authority for infectious
diseases and non-communicable diseases. In my study, the calibration sample began at
the end of February with the appearance of the first local outbreaks, which, unlike
in January, could no longer be completely controlled by the authorities through
quarantine measures. The end of the calibration sample marks March
30th.
The first political decisions that worked towards a comprehensive restriction of
social contacts in Germany can be dated back to March 16 [3]. For my investigation, I assumed that the
effects of the corona regulations on the case number statistics will manifest
themselves about 2 weeks later. I am guided by the official assessment of the Robert
Koch Institute, according to which the case statistics in Germany document the
situation around 2 weeks later [6]. The Robert
Koch Institute gives 2 main reasons for the delay in statistics. On the one hand, in
most cases it takes about 5–7 days between being infected and going to the
doctor, and on the other hand, another 7 days pass from the laboratory detection of
the infection to the notification of the illness to the Robert Koch Institute. In
Germany, the federal organization of health authorities can be held responsible for
the comparatively long transmission of infection numbers. The German health
authorities first aggregate the data at the level of individual regional districts
and only then report the case numbers to the Robert Koch Institute in Berlin [6].
For the counterfactual simulation of the disease development from March
30th, I used a branching process model based on the renewal equation
[1]. The methodological approach used in
this study builds on Nouvellet et al. [4]. The
model simulation is based on the estimation of the serial interval, which represents
the duration between symptom onset of a secondary case and that of its primary case,
and the estimation of the basic reproduction number, which describes the expected
number of cases directly generated by one case in a population where all individuals
are susceptible to infection. The serial interval was assumed to be gamma
distributed with parameters taken from the literature. Initial studies indicate a
serial interval between 4 and 8 days for the novel coronavirus [5]. The basic reproduction number for the
simulation estimates was also borrowed from the literature. The World Health
Organization estimates that the basic reproductive count for the new type of
coronavirus would be between 2 and 2.5 without state intervention [7]. Based on this, each infected person would
have to infect about 2 more people with the virus on average, which would lead to an
exponential increase in the number of cases.
Results and Discussion
Simulation results are summarized in [Fig. 1].
As can be seen from the illustration, the social lockdown broke the infection line
and greatly weakened the exponential increase in the number of infections. Without
political intervention, the number of infections should have been 20 to 50 times
higher than at the current level.
Fig. 1
These days, not only in Germany, there is much controversy about the usefulness of
government interventions in social life. The debate is often emotional and is much
more based on guesswork than fact. I have shown that there is currently no reason to
doubt the effectiveness of the social lockdown measures. Based on the results of my
analysis, it is obvious that contact restrictions are contributing to the slowing
down of the virus epidemic. Nevertheless, the question must be asked how long such
measures can be maintained without the economy collapsing or acceptance of the
population disappearing. Moreover, the social lockdown effect may not prove to be
sustainable because people do not want to stick to the strict rules for long and
neglect the risk of infection over time. However, since the disease is not yet
completely contained, such negligence can overturn the positive development of
infection dynamics at any time and quickly bring the development of case numbers
back to the point of exponential increase.
Germany is currently well positioned in the coronavirus crisis, which can be
attributed not least to the effect of the official contact restriction measures.
Other countries that decided social distancing too late or simply did not consider
it as a real option for action are now much worse off and have significantly
increased mortality rates. While the utilization of intensive care beds did not yet
reach its capacity limit in German hospitals even at the height of the crisis,
triage decisions had to be made elsewhere and patients had to be ventilated
selectively [2]. The German special route, of
which the rest of the world often speaks with admiration, is actually not very
puzzling in itself. Rather, the current situation in Germany testifies to the
effectiveness of the measures taken at an early stage, the success of which,
however, is fragile and prone to setbacks.
