There is a potential to write a long-read article about this hypothesis, but I will spill the beans right away. Looking at the map of Europe, there appears to be a very strong pattern which is as follows: the countries that have been hardest hit are found in 'old' Europe: Italy, Belgium, Spain, France, and part of the Netherlands, to which we should add the UK as well. On the other hand, peripheral countries (Ireland, Greece, Portugal) fared better, Eastern Europe was quick to act and has also done well, and the nordic countries equally seemed to be on top of the situation. The graphs with the excess mortality I drew based on Eurostat statistics of weekly deaths, clearly show this in the period before the fall outbreaks. Within the nordic and the western clusters, there are two notable exceptions, and this is their tale: Sweden and Germany.
For those who have travelled Europe, the reasoning isn't far-fetched. The countries that were hardest hit mostly have a Catholic background from which tight social networks came about, have a highly productive industry, yet shifted to a service economy in the last decades, and have an extensive transportation infrastructure that allows fast movement of goods and persons. The combination of close social and professional ties, and a dense and diverse population that is very mobile, provides all the ingredients for the virus to quickly spread. In addition, I fully acknowledge that demographics play an important role, and not to the favour of 'old' Europe, that has had a more pronounced baby boom which also has led to a large cohort of people of over 50yo, which is the prime group affected by coronavirus, certainly when not in good health. Obesity, diabetes, hypertension, and air pollution are well-known issues that negatively affect the overall health and life expectancy of these populations. Mortality rates are of course higher in people of over 65yo, but the very oldest cohorts are also much less mobile, and less numerous. Ethnic diversity and social segregation equally challenge these countries, as there is always burning ember and some groups are difficult to reach.
The picture in Nordic Europe is entirely different: the population pyramid resembles a pillar, not a pear, overall health is better, population density is lower, and a social-democratic sense of unity, combine with a mono-ethnic population, overtunes Lutheran individualism. In fact, there is a virtuous sense of individualism that relates the individual to the society: not merely in terms of following the horde, but really considering the contribution or burden one puts to society. It goes without speaking that it is no fairy tale where the good guys for once are retired Vikings, but anyone having been in contact with our Nordic friends will agree there is a different sense of responsibility and accountability. In Eastern Europe, including the Baltic states, stronger collectivism, less individualism, equally low population density and a poorer community life may similarly explain the difficulty of spreading the virus, although it is slightly more nuanced than that, but let us stick to 'old' and Nordic Europe for now.
Now there is an attractive model that may be of use to understand why the order of magnitude in both regions is different, called the 'logistic map'. Basically it says that the size of a population determines on its replication speed. This might also apply to the population of infected individuals: they fall sick and heal (which includes losing immediate immunity), much like rabbits are born and die. If the diseases spreads fast, they do not heal fast enough to prevent most of the population from being infected. Similarly, when rabbits procreate very fast, they will go to the upper limit of what is attainable in a certain area. This limit is what the logistic map delineates: the more people are infected, the easier and then the harder it becomes for new people to become infected. The reason is that once a very large number is infected, herd immunity occurs. We can formulate this algebraically:
I_t+1 = R0 * I_t * (1-I_t)
Where R0 is the replication rate (how many people one infected person will also infect) and I_t is the infection rate at time t. Note that other functional forms reflecting the same logic of a quadratic relationship could also be used. In this case, the steady state, where I_t = I_t+1, is then:
I = (R0-1)/R0
This is used to say that for a disease that has R0 = 2.5, like SARS-CoV2, herd immunity is reached when 60% has been infected and has some degree of immunity. It is important to see that this is within one community with frequent interactions. The immunity part is also quite tricky, as our hope is that SARS-CoV2 will remain in memory lymphocytes, unlike common colds and more like SARS and MERS, but of course we don't know what level of protection that will give. Without immediate B-cell immunity, we assume people can be reinfected and may pass on the disease, even when not falling sick again. So no immediate immunity, but possibly immune memory, is what is behind this logic. As R0 is determined by the number of contacts, and we have argued that there are structural, economical, and cultural differences between the regions in this respect, total infections will be lower in Nordic countries. Hence the threat is not the same, or in other words still: in the 'old' Europe, behaviour will need to change more than in Nordic Europe. The distance from normality is larger.
Now strangely, among the four largest Nordic countries (Denmark, Finland, Norway and Sweden), the epidemiological pattern of Sweden looks more similar to that of 'old' Europe, and of the larger countries in 'old' Europe (Belgium, France, Germany, Italy, the Netherlands, Spain, and I add the UK), Germany looks more similar to the Nordic countries. This leads me to conclude that German policy should be regarded as a good practice, and Sweden as a bad practice. Of course, we know that German culture is stricter than southern cultures, and that the city of Stockholm is not too different from capitals to the south, and retirement homes in Sweden were affected by a stroke of bad luck, but the fundamental challenges remain. In Germany, there have been outbreaks in the meat industry, for instance, and in religious communities, but they have been efficiently contained. In Sweden however, there was an attempt to separate the older from the younger population, that has failed, and older people have not been given the necessary care in order for them to survive.
