Published in El Pais, 10 Abril 2020.
In a serious quest to find measures to protect their people, governments all over the world have come up with all kinds of strategies. The most used ones varied between a full quarantine (Bolivia), an intelligent lockdown (The Netherlands), or to only social distancing only (Sweden). The objective behind these strategies was to reduce the number of close contacts between people. The economic impacts are disastrous, and hopes are that all will be over soon, but when? Questions are raised if the measures are enough and will effectively work. Big differences can be seen between countries’ death rates and one can say that it is because the outbreak started later. But this is not explaining all. Although everything started in China, the death rate was 2.32 per million residents while at this moment, Spain is leading the infamous charts with more than 251 deaths per million residents. The big question is why?
The older the worst
It has been shown from the beginning that the older is the person (65 years or older), the higher the chance that you will get infected with COVID-19. And if you are sick, the older you are the higher the rate you will die of it. That said, this means that countries with a higher number of older people will also have higher death rates. In China only 10.9% of the population is older than 65 years, while in Italy and Spain it is respectively 22.8% and 19.3%.
In the graph, the percentage of the population over 65 years is crossed with the logarithm of death rates. The death rate per million is expressed as a log, meaning that for example 2 is 102 equals 100. This was done to show a clearer graph and for statistical analysis purposes. The three straight lines are linear regressions to show the correlation between share over 65 years and the death rate. It shows Asia, where the virus is retrieving and not that much of an issue. Europe where the situation is still causing deaths and Americas (Including North America) where measures were taken early, and hopes are it will get under control.
One thing that strikes the attention is that the death rates are lower if the 65+ share is lower. Running the regression on all countries and shows that 45% of the variation of the model (R2 =0.45) is explained by the death rate in relation with the share of 65 and older percentage.
One thing to bear in mind is that the outbreak has not finished. Therefore, we can assume that the numbers in Europe and Americas will still go up. Looking at the graph, the Europe line will go up or go steeper. The Asia line will probably only move slightly up. The Asia line will probably only move slightly upward. But we still have the question for the Americas. Since many countries in this region have young populations, the threat may be limited to low. There would only be greater danger in countries with a greater number of people over 65, such as the United States and Canada, so their line could rise or become steeper.
The virus also spreads faster in older populations
More older people in a population increases the death rate. At the same time, one can assume that the numbers could increase the outbreak rate. A young person can get infected but not have any symptoms, including no coughing or sneezing and thus has a low spread rate. On the other hand, an older person will have stronger and visible symptoms that could spread the virus more rapidly.
What will happen in young populations?
Although the model only explains 45% of the variance, and other variables may be needed to control the outbreak, younger populations are probably safer than the older ones. Looking at for example Bolivia, where only 7% of the population is over 65 years old, it probably means that, with the right measures, their death rate could be limited to about 2-3 deaths per million residents. With a population of 11.5 million this would mean 23 to 34 deaths in total. After all China’s death rate with 10.9% of 65+ stayed on 2.32. That said, since many of the countries with young populations are also the most economically fragile, they may have an opportunity to reduce extreme quarantine soon and resume daily activities sooner than countries with populations with higher number of older adults.
What is happening in Japan, Iran and others?
A few interesting outliers or exceptions are Japan, Iran and Ecuador. Although Iran has a very young population, its death rate is very high, and it continues to grow. A third case is Ecuador, which has been drawing attention in the news for its high mortality rates compared to other South American countries and with similar quarantine measures. What is going on these countries? Even though we lack data to check specific city information, it can be explained by: a) the higher number of 65+ people in certain cities and so, potential infection of COVID-19; b) high people density-rate as closer to each other also affects infections; c) strict measures and disciplined behavior like in the case of Japan.
Of course, one can think of many other reasons that are relevant to the speed and severity of the COVID-19 outbreak. Nonetheless, these numbers explain the relation between age and the number of deaths that could explain in part the difference between the countries. And this would be a useful basis for taking the following return to activity strategy or maintaining quarantine.
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