Concerns about the Covid-19 epidemic should be focused on the economic and social impact that it is having. From the perspective of public health or personal health, fears could be of a lesser magnitude. Control activities are being carried out effectively and the disease tends to be mild in most people.
From a scientific perspective, the epidemic is a new experience that enables us to learn important concepts. Unfortunately, it also causes some cases of severe illness and some deaths. In recent weeks, we have seen that global coordination is possible and that technical information can be shared easily. We have found that public health surveillance systems have the capacity to respond. Initially, we thought that it was impossible to contain the epidemic; China has shown us that it is possible. In the Chinese province of Hubei, where everything began, new cases have been dropping gradually for days. In addition, the behaviour of the epidemic in the other provinces of China is adequate, the total number of cases is low, and it has been controlled quickly. The epidemic can be contained. We can prevent health systems from collapsing.
In the Group of Computational Biology and Complex System at the Universitat Politècnica de Catalunya (UPC), we are monitoring the data published by the World Health Organisation on a daily basis. We use mathematical models to predicthow the epidemic will behave in the next days and weeks. In a situation that is as new as this, mathematical models are particularly valid for short-term predictions.
The behaviour in all the provinces of China and in all countries is not, and has not been, an exponential increase in cases as some media claim. In all cases, the temporal evolution in the number of people infected is described correctly by the Gompertz curve. This equation expands more slowly than the exponential function and tends towards a maximum value of cases, as observed in all Chinese provinces. In addition, using models in which we study behaviour individual by individual, we can understand what makes the epidemic advance in a contained way, as described by the Gompertz curve. These models corroborate that lockdown of the population and surveillance of new cases is the right strategy.
In Spain, the epidemic will probably continue to grow for several weeks, but at an increasingly low frequency. This means that the number of new cases for each detected case will drop. This behaviour may last until the end of May. Consequently, we should remain calm before the increase of cases that will emerge. The control activities are being carried out well. We want to express our confidence in the work of the epidemiologists, public health agencies and health centres. As citizens, we should be disciplined and patient.
At international level, the perspective is hopeful as local expansion is being controlled, even though the virus has reached many countries. Even in Italy, South Korea or Iran, where the incidence is high, the number of new cases for each detected case will drop. In other words, the expansion is really being contained.
We can make predictions about the epidemic in places for which we have around two weeks of accumulated data, but we cannot predict whether the epidemic will start in other countries; we have to be on the alert. Mathematical models are not a crystal ball to foresee the future; they only help us to understand the situation.
From a mathematical perspective, the alarm created by coronavirus is incomprehensible considering that other epidemics are overlooked. Tuberculosis causes a million and a half deaths every year! In Catalonia, 1,200 cases of tuberculosis are detected annually, which is a very high number. In 2018, measles caused over 140,000 deaths in the world and is having catastrophic effects in some countries such as the Democratic Republic of the Congo, where from 31 December 2018 to 5 February 2020 it caused 334,360 cases and 6,326 deaths. The dengue epidemic in America caused over 3 million cases in 2019. Viruses and bacteria do not respect borders. The current epidemic has shown us that cooperation and working together are vital for the safety of all.
Daniel López Codina, Group of Computational Biology and Complex System at the Universitat Politècnica de Catalunya (UPC)
Article published in El Periódico on 10 March 2020