Why Germany has a lower coronavirus case fatality rate than Spain or Italy: these are the hypotheses

In full swing, those affected by COVID-19 grow by the minute in Spain. At this point, with the country in alarm, we have 335 deaths and more than 9,000 infected. Germany, by contrast, has more than 6,600 and only 14 deceased. Why?

In other words, with just 3,000 affected, the case fatality rate seems to be much softer. It is still too early to know why, something that will probably only come to the fore in the future, with some perspective. However, at this point we can only guess and launch some hypotheses. These are the ones that have the most strength for now.

The figures for Germany, Spain and Italy, compared

Let's start by putting the cards on the table. According to the correspondents, Italy registered almost four hundred more deaths yesterday, reaching more than 1,800. Italy, after China, is the most affected country in the world, with almost 25,000, followed by Iran. It is also the country with the most deaths in Asia. Spain, for its part, is in fifth place, with more than 9,000 affected and more than 300 deaths.

Germany has recorded almost 6,000 cases and a positive number of just 13 deaths is waving. Curiously, South Korea, which had more than 8,000 cases, has only registered 75, almost three times less than in Spain, it is undoubtedly the country that has best managed the crisis. However, due to the size of the country and technological and cultural differences, Germany may better serve as a reference for comparison.

Because, after all, it is what we want: to get as close an idea as possible of what is happening. With these figures facing it, it is important to note that the epidemiology of the virus often causes them to converge in similar numbers over time. But, as we reach stabilization, there are some interesting differences that can help us learn more about its evolution.

The oldest population hypothesis

There is one thing that the virus has shown: the older population is the most disadvantaged in terms of consequences. This is not unusual. In fact, it is the most normal thing. In other similar diseases, the risk groups are clearly the highest. They are also among the majority of deaths. Although it is still early to know, some research projects, such as this one Demographic Science COVID-19, Posted by Melinda Mills et al how preprint at the Open Science Center, they show a certain relationship.

According to his work, the structure of older people are directly involved with higher mortality rates from the disease. Deaths are mainly concentrated in older people. This fits in with the situation in Italy, where the virus began to spread in areas with a larger population. It also fits in with the UK results, where an older population is associated with comparatively higher mortality.

1/12 How does #Demography impact # COVID19 deaths? In new pre-print, we illustrate how older population age structure can interact with high mortality rates at older ages to produce a large # of fatalities, as in Italy. https://t.co/G2fDFI8vN0 #poptwitter #epitwitter

- Jenn Dowd (@drjenndowd) March 15, 2020

While, in countries like Germany or South Korea, between 80% and 90% of cases were under 60 years of age; in Italy only 40% of cases were in that young age range. However, if we review the demographic data we notice a rather curious fact: according to the statistical data collected in Index Mundi, in Germany those over 55 make up almost 36% of the population, while in Italy they reach 34%, less than in Germany. In Spain, in fact, they are even less, with 29%. What happens then? The answer seems to lie in the social structure.

The hypothesis of "at home until 30"

Go ahead that this is a somewhat crude example that aims to serve as an example of how family and social structure can make a difference. Difference such as that existing socially between Germany, Italy and Spain, within the family. According to INE data, collected by the press on several occasions, young Spaniards do not leave home until they are 30 or older.

A similar situation occurs in Italy. The figures estimate that at least 20% of the young population lives with their elders in this country. By contrast, Germany is known for the independence of its younger population. Something similar happens with other northern countries, such as Sweden or Denmark, where young people who live with their parents do not even reach 5% of the population. In Germany, according to Eurostat data, young people leave home at age 24, almost seven years earlier than in Spain or Italy, and their life apart from the original family nucleus is much more common. Only a small percentage continues to live with their parents.

The lowest case fatality rate of the virus also coincides in all these places. For more weight, the model proposed in preprint we were talking about, Brazil, Nigeria and South Korea fit this hypothesis. And what can be the explanation? The contact, obviously. The 2019 nCov, the virus that produces COVID 19, is a highly virulent virus.

As almost everyone knows by now, it is not transmitted by air, but by droplets of saliva and other fluids, through contact. Furthermore, it is highly infectious, with a new infection rate of almost 3 (three people per patient 0). As if that were not enough, it can be transmitted, it is suspected, by asymptomatic carriers (that is, they do not show the disease). The virus takes a long time to incubate and can be transmitted at various stages. Many of the transmission mechanisms are still somewhat mysterious.

It is legitimate to think that direct family contact, especially among young people, who are the population that is most likely to carry the virus without showing symptoms and the oldest, who are among the population at risk, is an important factor in the transmission of COVID-19. However, it is still too early to reach a scientific consensus.

The health oversaturation hypothesis

There is also a suspicion that sanitary oversaturation could be a driver of the most dramatic situations. Are hospital collapses leading to more deaths? As with all serious illnesses involving the respiratory system, proper care, the use of respirators and specialized medication are vital to ensure survival. If these resources fail, as has been shown in several studies, such as this one from the University of Ontario, mortality skyrockets.

This same situation is what the assigned reporters in China drew. It also seems to describe the news of Italy, Spain and Iran. Here are the best possible examples of the hypothesis: Is medical oversaturation wreaking havoc? Can mismanagement coupled with rapid expansion critically leave a country without health resources? Given this idea, which does not seem far-fetched, there are some examples that seem to contrast.

For example, the UK, like Spain or Italy, is finding itself lacking in resources (such as respirators) to treat COVID-19 respiratory failure. In Italy they even use 3D printers to create respiratory valves. However, the progression figures are smoother than in the other three examples. Perhaps it is too early for it to be, comparatively speaking, a benchmark? The truth is that it takes more time to work with this idea. We are still mired in the maelstrom of the problem, with curves still growing and patients on treatment. What we can observe is the battery of diagnostic and containment measures, the tests, that have been carried out since the beginning of the pandemic. Have they worked?

The systematic diagnosis hypothesis

Without going into criticism, we can point out the notable differences between different countries when it comes to dealing with the disease, especially in terms of diagnosis. Thus, while South Korea has turned the tests into an almost systematic question, in Italy the health oversaturation has given dramatic scenes. Are these differences significant? Yes and no.

For sample, a button. Returning to the figures for Germany and South Korea, the Asian country has been much more verbose in detections and treatments. While still efficient, Germany appears to have shown a slightly laxer attitude in prevention and treatment. However, with similar numbers of infections (6,600 vs. 8,200), their deaths are far fewer.

This time it plays an important detail, and it is the fact that the more tests, the more positive cases. This obvious point indicates that Germany, as it happens with other European countries where the coronavirus test is not done systematically, could have more cases than have been registered. On the other hand, it is rare for a death case to pass in Germany without having been tested for COVID-19 by protocol. Since the pandemic began in Korea and Germany, all suspected cases, including deaths, have been reviewed. Finally, they could have more cases in Germany, even, than Korea, due to the asymptomatic carriers, for example. And, even so, it seems that the deaths are less than in this country. Why?

Social structure seems to be the determining factor

To reinforce the idea that social structure is a determining factor, two economics professors at the University of Bonn, Moritz Kuhn and Christian Bayer, recently developed a model that can explain some of these variations based on the number of young people who they still live in the parents' house. This one, like Mills's, fits pretty well with the virus's current data and progression.

The most disturbing thing, however, is the forecast launched by researchers: countries like Serbia, Poland, Greece, Portugal ... could see themselves in a crisis very similar to that of Italy. As the social structure hypothesis picks up moment, the concern to slow down the growth curve of the disease becomes more and more crude, although in China they seem to have succeeded. Another detail that the experts point out is that, over time, mortality tends to equalize between populations, regardless of early forecasts. It is what is known as stabilization of the disease. With this they warn countries like Germany, with low case fatality rates, to be vigilant, as the tables could quickly turn.

For further complication, the example of Germany and South Korea are contrasted with that of Japan: this country is famous for its high rate of older people and the coexistence of family groups with a large age difference. However, it is one of the countries with the least infected, just over 800, and just 27 deaths. Statistically speaking, the case fatality rate is much higher than in Germany or Korea, but its low number of infections is surprising. Why is there this exception? How has the spread of the virus in Japan stopped? These questions will represent an important review of the hypotheses.

What is more, it may provide a warning sign for those countries where the elderly and the young live close together, how important it is to contain the virus there early on. These countries are within Europe in particular such as Serbia, Poland Bulgaria, Croatia, or Slovenia. pic.twitter.com/S53Y8bSPci

- Moritz Kuhn (@kuhnmo) March 13, 2020

Family nuclei with a high interaction between older and younger people, who tend to have more opportunities for contact, but less prevalence of the disease, become units to observe carefully.At the moment, countries like Spain are trying to reduce the speed of contagion due to a practical health issue: there are not enough resources to be able to serve everyone.

In this aspect, an infected family nucleus is doubly worrisome since we are not talking about a person, but an entire family, with the difficulties of treatment and isolation that this implies. It also multiplies the chances of contagion. As we said, it is still too early to launch a clear message. But it is worth noting that it is taking on an important role as a determining factor in the progress of the disease.

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