Researchers linked to the Center for Mathematical Sciences Applied to Industry (CeMEAI), with support from Litter Institute, developed a mathematical simulation system which allows us to outline different scenarios of social isolation for cities in the State of São Paulo. The isolation levels indicated by the program vary depending on the characteristics of each municipality, such as the rate of spread of the coronavirus in the regions and the capacity of the health system to absorb new cases that require hospitalization. Professors Paulo José Silva, from the Institute of Mathematics, Statistics and Scientific Computing (IMECC) from Unicamp, Tiago Pereira and Luís Gustavo Nonato, from the Institute of Mathematical and Computing Sciences (ICMC) from the University of São Paulo.
According to Paulo Silva, the system is based on the recognition of social isolation as a necessary tool to reduce the rate of contagion of the new coronavirus and maintain the capacity of the health system. In addition to this, the researchers sought to include in the calculations the possibility of combining periods of controlled opening with more or less restricted closures, a concept called intermittent isolation. In this way, for each city it would be possible to design opening and isolation scenarios considering the characteristics of the municipalities and the goals set for each region.
"Looking at the literature, we have realized that it will be necessary to alternate between periods of more mitigation, more interference, with more normal periods. So, what our system tries to define is what are the levels of reproduction of the virus that society would need to reach , trying to combine these three objectives at the same time: not letting the health system explode, not leaving a city closed indefinitely, if possible, and leaving part of the state's economy functioning over periods of time", explains the professor.
Different strategies for cities
Based on data from the current situation of municipalities, the system presents public managers with a simulation of what the ideal social distancing protocols would be, from the mildest to the most severe, so that the coronavirus contagion rate remains within the parameters defined for maintenance. the capacity of the health system. In one of the scenarios simulated by the researchers, Campinas and Sorocaba would present similar isolation trajectories, with gradual opening until the end of 2020. In the same period, Ribeirão Preto would experience an alternation between openings and closings (see graph below).
By taking into account aspects that vary depending on the evolution of the pandemic in the state, such as registered social isolation rates and the capacity of the health system, the results of the simulations presented by the system may vary constantly. According to Paulo Silva, despite offering indications for the future, the system presents public managers with a snapshot of the moment. "The decision to be taken has to be reviewed every week, or every two weeks. Every time there is an increase in the capacity of the health system, or when the set target is not reached, if there is an increase in the number of patients, a new simulation will be necessary that will suggest a strategy for the next few days, this would happen all the time. It's not something like 'do this and it will work', because the scenario is dynamic", he analyzes.
Although the system points out ways for there to be periods of easing social isolation, the professor warns that the measures are only possible in a scenario where the coronavirus contagion rate is controlled. Therefore, he argues that isolation measures must still be observed: "Until now, we have not achieved, anywhere in the country, a virus replication rate lower than one, necessary to control the disease. Therefore, the We see throughout Brazil that the disease continues to advance, in some places more slowly, in others more quickly, but it continues to advance. And there is no alternative, if you are unable to achieve an isolation that brings the rate below one, The only solution is to do as much isolation as possible."
Constant dialogue with public managers
According to Paulo Silva, the researchers' objective is for the system to be available to public managers, both municipal and State, to contribute to decision-making regarding isolation measures. However, he argues that the adoption of the system depends on proximity and dialogue between managers from different regions and government bodies due to the complexity of the program itself and the responsibility involved in the decisions it makes possible.
"It is not a simple system, so the ideal is for there to be a constant dialogue between those who operate the system and public managers, because there are decisions to be made. For example, what is best? Leave Campinas in the same group of cities and Jundiaí or Campinas and São Paulo? What is the ideal level to leave the health system unburdened? Closer or further from 100%? So to run a system like this it is not just about operating a program, it is necessary to have a conversation between managers and those operates the program"
According to the professor, public managers from municipalities and the state administration have already shown interest in learning about the system, but the dialogues are still in the initial phase. But he reinforces the importance of improving social isolation rates and reducing contagion rates to control the disease. "A system like this only works if we can achieve greater isolation than we have been able to achieve. Otherwise, we don't even need to run the system. There's no need for mathematics, just common sense", concludes the professor.
