Two Brazilian scientists are using physical models of dynamic systems, used in astronomy, to help predict the behavior of the coronavirus in Brazil. The idea is to contribute with the authorities and doctors to prepare for the covid-19 epidemic, as it happened in countries that faced the disease before Brazil.
The model was formulated by researchers José Dias do Nascimento, physicist at the Department of Theoretical and Experimental Physics at UFRN (Federal University of Rio Grande do Norte); and Wladimir Lyra, an astronomer at New Mexico State University, USA.
The work uses equations known to astrophysicists and astronomers to understand phenomena in nature. Brought to the reality of the pandemic, it outlines scenarios in the face of disease progression in more optimistic and pessimistic perspectives.
"Astrophysics deals a lot with nonlinear processes, and in fluid dynamics research, she had even used models originally developed for the dynamics of biological populations, such as the predator-prey model – a model that was developed in biology-mathematics to study populations of predators and prey in an environment. Some astrophysical processes follow the same dynamic, "says Lyra to Tilt.
Nascimento states that the model used is called SIR, which divides the population into three parts: Susceptible (to contract the virus), Infected and Removed (cured or killed), hence the acronym.
"It is a simple and well-established model in physics since the 1970s. It has entered with great force in the studies of spreading diseases by viruses. Physics has variations of this model, and what is new in this model is the acquisition of data in real time and recalculations of the parameters for forecast ", he says.
The dynamic systems used here are the same as for weather forecasting and the analysis of planets and stars, based on concepts from physics and mathematics.
"This dynamic system, with the possession of new data, can evolve and know what the next step of the system's variables is. That is, with it we can describe each of the particles at that moment and know where it will be in a second moment", he completes .
Projection of the number of deaths by the coronavirus, according to a model developed by Brazilian researchers
How the idea came about
Initially, there was no forecast to do work in the area. "This started with a conversation with us about data science, but it has become our main concern for a week now: running and forecasting scenarios for Brazil. Each country is concerned with running for its country, and we, as Brazilian scientists, even though we are here in the USA, we have looked mainly at the consequences in Brazil ", says Nascimento.
The researcher says he analyzed similar forecasts from other countries that have been facing the epidemic for longer than Brazil. It shows that the country can follow a worrying path.
"In Italy, even with the warning from the Chinese, it took a long time to have the reactions. That was obviously a problem. In China you can see today that the war between isolation and many tests was impressive. In South Korea, the isolation was not so great, however, they tested thousands of people per week which corresponds more than the United States tested per month ", he says.
In Brazil, the worst scenario, one where nothing is done by the authorities and life goes on without restrictions, predicted until the death of 2 million people. This probable scenario is that of a collapse that may arrive in late April or early May.
"This is a scenario, let's say, pessimistic – when this curve grows and affects the entire population at the same time. So this kind of thing ends up causing a suffocation, a suffocation of hospital structures", he says.
"This is the problem, and we are seeing this in the graphs, if we do not have many tests and without the care of severe isolation. So we will not be able to lower this curve, and the cycle of susceptible people infected and dead will continue as on Italian models, without any restrictions ", he adds.
Nascimento also says that he sees problems in Brazil, for example, in the question of tests. "We have an incredible delay in this, which will obviously be a determining factor of what will happen in 15 days, when today's infected people started to appear effectively in the distribution of deaths, of the most serious cases," he says.
At this point, the scientist says that he is looking for new parameters to reach an even more precise number.
"We need these parameters, such as the number of hospital beds, which are the technical bottlenecks and their variables in the real system. With that, our system is confronted with the offer of hospital care, and understands how the curves will emerge. That's what I'm doing now when talking to medical scientists ", he says.
Nascimento, however, warns: "There needs to be a deeper study by infectologists, people who actually study the area. We use this model for physics problems, but we don't know how to solve it. Interpret the data and suggesting public policies are things that need to be discussed, obviously, in a multidisciplinary committee ".
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