A rising number of questions about the corona virus epidemic are currently reaching me. Therefore I have decided to show my perspective in this text. I have to give a full disclosure that I’m not a medical doctor nor expert on viruses or epidemics. However I am a statistician and sustainability scientist. As such, I am able to detect patterns and interpret data, and I’m interested in solutions and normative perceptions. There are other medical experts that are currently giving us their perspective, and I highly encourage you to rely on a diversity of information. The Internet is full of wrong information, and in these times it is very important to rely on information that at least tries to maintain on a high quality and long established standards. To me, this includes primary scientific literature, and the established press, including such media as the BBC the New York Times, the Washington Post, the South China Morning Post, German Tagesschau and other media that have a long-standing tradition of interpreting information. I consider also to be good to rely on the numbers on Wikipedia, which are more or less up to date despite some smaller quality issues, but the percentage increase is a vital number that you can find there.
It is also important to highlight that there is a difference in much of the way we see information in these days. Hence you have to pay attention on the wording of what I am going to write here. There is a difference between things that are known information that is published in medical studies, information that is estimated from previous data analysis and rough guess work that is necessary because of the great unclarity of the current situation. I will differentiate this blog entry based on the short term and the long term perspective; there is an in between perspective where you can still have rough estimates based on the current information which I will also highlight.
The coronavirus is now a global pandemic and this may preoccupy us for a long time. However, what this will mean in our day to day business we will have to explore individually. In my opinion, we have to be very careful now. Each and every single one of us should act, as a colleague mentioned, as if we have the virus. We should thus be in our actions as careful as possible, avoid all community contact, and basically bunker down at home or take solitary walks. I know that this is hard measure for many, and my kids are sitting next door being already being completely bored out, but this is a time of crisis.
The developments in China show us how with Draconian measures the Chinese government with the cooperation of the citizens has managed to dramatically reduce the numbers of the virus. This first drastic epidemic in China has many lessons to learn for us. I will try to explain the different phases that this type of infection typically takes in a larger population, based on the analysis of the current data at this point in time. This is an imperfect approach and has many ramifications, however I want to highlight that as a statistician I am very conservative. The first phase that you have in the spread of this virus within a population or country is quite chaotic. The medical experts may have not yet detected the majority of cases, due to the often long periods of up to 2 weeks of incubation in combination with the fact that many of the affected people show mild symptoms which makes the early detection of cases difficult. I will not go into the complex start of the crisis in Wuhan in China but despite all the discussions about the reaction of the Chinese government I can only extend my compassion to the citizens of the Wuhan region and the whole of China for enduring these drastic measures to contain the spread. We all owe them big time.
This phase 1 shows the first drastic growth of infection and is often characterized by a growth rate of around 50% from day-to-day. Many European countries were in the last few days in this space. Once the spread within a given population is better understood, and local clusters are identified, the increase in patients from day to day becomes often more tamed. Of course this relies on -as we now see- Draconian measures in many countries, but it helps to slowly drive down the increase in patients. This is an often very difficult phase as you are still looking at a basically dramatic growth pattern that is very high, and where every day of in action may lead to twice as many cases for each two days. I will not go into the details here what proper reactions are, I can only highlight that I personally rely on extreme social isolation right now which means that my family is at home and we meet no one else.
If the growth is getting smaller over several days, and ideally the rate of increase in cases is linearly decreasing as we saw in Wuhan region, then this is a sign for optimism, and what I coin phase 2. The numbers can still rise by 10% of less in daily increase, which is probably due to smaller undetected case clusters or people breaking the general rule of extreme social isolation and other factors. This phase of reducing the numbers below 10% increase from day to day takes, judged from the available data, several weeks if not one month. Around this time, you would have ideally reached a point within the mortality rates that is not going to rise dramatically further. The problem with mortality in this virus is that if people are sick, they typically start dying one or two weeks after they showed symptoms. Since on average the people do not show symptoms after being infected for almost a week, it takes a long time -up to three weeks- until the real mortality rates are showing.
An appeal for care seems appropriate here, please remember that catching this virus is not a death sentence. Instead the mortality is higher as with the flu, but lower as with Ebola. There are other cases of viruses even more dramatic, and while the death rate through the common flu is still higher in total numbers right now, this may change if more people get infected with Covid. Current studies that are based on localised populations and often smaller samples show however, that younger people seem to be less affected, and we should be very careful regarding older people as well as people with medical conditions, such as asthma, high blood pressure, cardiovascular conditions, and so on.
Coming back to the different phases of the virus, there is a third phase that is probably reached after several weeks, when cases go dramatically down. It is admiring how the Chinese people were able to reach that milestone after basically two months of extreme measures, and the situation in China right now gives reason for hope. A similar situation could be achieved through extreme intense genetic testing, but one has to be aware that the technical capabilities that are available in South Korea are not available in other countries. South Korea has full-blown industry focusing on genetic analysis, and many genetic samples are sent to South Korea since decades for analysis. Hence their capabilities when it comes to the genetic testing and detection of the virus is probably unprecedented. It is at this point unclear whether genetic testing in technically advanced countries such as Germany will have enough long-term resources to allow for a detection of the virus at a scale that happened in South Korea. A better option for many countries might be CT scans. The Chinese response teams implemented an often highly efficient system in scanning many patients with this technology, which is available also in smaller hospitals and countries that are less capable regarding their medical system. Such CT scans allow with her relatively high confidence a detection of patients even if they only show mild symptoms that would otherwise be not detected. Hence this might be an alternative option although it is of course not at all as sensitive as the PCR tests that are currently pursued. Whether other and faster tests will become available should be hoped for, but it’s right now not clear. It is quite unclear how long phase 3 actually takes, but I would suggest that at some point social isolation may become less extreme, although this would not be recommendable. This is still not the time for intervention fatigue, instead we need to be clear that everybody is still distancing themselves for weeks until the disease is gone or at least localised. This is the short term perspective that the epidemic currently had in China and it might give us an idea of what is going to come in other countries in the next few weeks or months.
Short term trends
The numbers in Italy are most likely going to increase, and it is very unfortunate that the Italians missed the early cases which is -and this is very important- entirely not their fault. They were in a very unlucky situation, and now try to react appropriately. Similar increases are currently happening in many other European countries, including Germany and will most likely go on for at least a week. In a few days we may see whether the increase in infected people will go down, meaning that we have less percentage growth from day-to-day. This could be expected with some optimism; however, we will have to wait out the measures taken by the governments who are currently working on it. It is very unclear what is happening in the United States right now, as testing is certainly not extensive, and occasional anecdotical descriptions of community spread within several states are the reason for great concern. Likewise the numbers from other countries at this stage are very unclear, as they may not have detected the cases get, or their form of governance may prevent them from sharing the full extent of the natural disaster.
The long term perspective
It is very difficult to know anything long term at this point. There are suggestions that this virus will become a seasonal infection such as the common flu, which may be possible. However, I do not know whether the general population would be willing to endure a virus with a 0.9 mortality at best. And this brings me to another point, that is the rate between the mortality and the medical system within an affected population. The extensive testing from South Korea shows that there might be a mortality rate of 0.9%, which is quite optimistic. In comparison, the rates in China are much higher, while the rates in Germany right now are much lower. There is much speculation about these differences, yet from a simple log linear model this can be easily explained. Germany is at an early stage of the viral spread, and much may be undetected right now or is rather recent. Also, as I’ve already mentioned, people will start unfortunately dying in one or two weeks at a much more extensive scale. I hope I am wrong to this end, but unfortunately I think it is very likely that death rates in Germany will increase substantially. In Wuhan in comparison, the case is completely different. Here the medical system was widely overwhelmed by the virus, and the capacities of the medical facilitation’s were completely overwhelmed by the epidemic. That does not mean that the efforts of the medical personnel and the government were not extensive, they were in fact absolutely impressive! However, no medical system is able to cope with such a high rate of infections. Once the system is exceeded, the death rate is going to increase. This is simply rooted in the fact that 15% of the cases needs pronounced medical attention in hospitals, and about 5% are critical. Without oxygen and other respiratory aids, these people have a much higher chance to die. We have right now -according to official numbers- around 25,000 beds of for intensive care in Germany. If you imagine that 15 to 20% of cases or maybe even just 5%, may need the space, this would mean that we would face a situation where about 125,000 to 250,000 infected people, which would need intensive care units for about two weeks. In an optimistic case this would mean that we would have about 6 million infected people within one year. Everything above this number would exceed the capacity of the hospital beds that we have for intensive care, and while there are different suggestions from experts I am worried how we would deal with exceeding the capacity of beds we have in hospitals. This does not include the consideration how this will play out in other countries, for instance the US, where medical attention is also not available to many people, let alone countries in sub-Saharan Africa. It is widely clear that such simple calculations make a rather complex development oversimplistic, but at this point I did not understand how we have enough beds for 58 Mio infected people within a year or two years.
Ending the curve
Flattening the curve would hence in Germany work if we consider this on 9-10 year timescale. I do not believe that it will take so long to obtain this disease, as a vaccination might become available, however I do not believe that any country would accept a mortality rate of 3 to 4% within their population. If 3 million people die in Germany because of this virus, this would be an issue. Current estimates in the US consider at least half a million dead people, and this would certainly lead to more severe reactions than we see right now. Hence I think that flattening the curve is not enough, we need to end this spread. This is now a question of global responsibility, and we have to try to get rid of that virus. We had other success cases such as in smallpox, which was a Herculean effort, but this is now the time where the behaviour of each and every single individual person is very important. We need to work together as humankind.
There are people that suggest that a warmer climate, or UV radiation may help us to take this virus, but this is totally unclear right now, and looking at the numbers from warmer countries I would not bet on it right now; although the data does currently not allow more than vague assumptions . I currently guess based on the regional and sparse data, that temperature will not affect this virus severely, but this is as I said guesswork. One recent study highlighted that temperature may play at least partly to our advantage, but this is widely unclear at this point. Maybe in one or two weeks this is more conclusive. Talking about Mutations at this point does not make sense, I am as I said no expert, I can interpret the data, but here an epidemiologist or virologist may know more, and they are pretty clear that it is pretty unclear.
How to go on?
Minimising the spread within the population, measures such as genetic testing and at a later place CT scans and a continuous and enforced extreme social isolation are the best instruments that we currently have, which is no easy step. Many people have anxieties to this, but this is not going to be the end of humankind. I repeat, world keeps turning. The chances for the individual being affected are very low, and we will come out of this on the other side. The question is now what is the price that we want to pay, and are we willing to make sacrifices and compromises in order to contain the spread of the virus. First and foremost, I think the main question guiding our life should be whether our actions now help to end the spread of the virus. We need to put everything else aside.