RIO – A Unicamp study states that if the level of isolation in the state of São Paulo remains below 60%, total blocking will be the only solution to contain the transmissibility of the new coronavirus.
It is estimated that at the end of June São Paulo will account for 53,500 new infections per day, with 20,800 daily cases in the capital of São Paulo alone. During this period, the number of new cases is expected to double every 11.5 days for the state and every 12.9 days for the capital, in the coming weeks.
The study was done considering the real data of growth in the number of cases over the last month, which indicate a contagion rate of 1.49 for the state and 1.44 for the city of São Paulo. That is, at the end of April, every 100 São Paulo infected people transmitted the new coronavirus to almost 150 people, on average.
The mathematician Renato Pedrosa, professor at the Geosciences Institute at Unicamp and coordinator of the Special Program for Science, Technology and Innovation at the São Paulo Research Foundation (Fapesp), worked considering a mathematical analysis of linear regression, in combination with the real data of growth in the number of cases over the last month, with the information from the health departments.
The work was carried out from the 8th to the 10th, with projections from the previous fifteen days, and continues in progress.
– The number of daily cases in São Paulo will be close to the total number of cases we have accumulated to date in the state. The projected values ??indicate that this month the public health system in the Metropolitan Region of São Paulo will reach the limit, as the level of occupancy of ICU beds is already above 80%. If the isolation is not expanded urgently, the state will have to adopt more drastic measures of containment, as occurred in Italy, or the situation will become untenable – says Pedrosa.
The researcher assesses that the isolation needs to be done continuously:
– Today’s results are the consequences of previous weeks, so the isolation needs to be done continuously, as well as the use of masks, otherwise the numbers will skyrocket – he reflects.
The estimates were made using a model developed by Pedrosa and described in a preprint version available on the medRxiv platform (not yet peer-reviewed). The model allows estimating the transmission dynamics of COVID-19 in different locations, taking into account climatic variables (temperature and absolute humidity), population density and the timeline of the onset of the disease (date when the country or region reached the mark of 100 cases).
To develop the model, Pedrosa used data from 50 US states and 110 other countries, including Brazil. Countries were selected for which sufficient information was available to calculate the exponential growth rate in the period when the hundredth case of the disease was recorded.
The meteorological information was obtained from a database of the National Oceanic and Atmospheric Administration (NOAA), an institution that is part of the United States Department of Commerce. Data on the expansion of COVID-19 until April 10 came from two sources: the Center for Systems Science and Engineering at Johns Hopkins University (United States) and the European Center for Disease Control and Prevention, based in Sweden.
– Initial studies suggested that the new coronavirus would find it more difficult to spread in countries with hot and humid climates. However, according to this model, the effect of climatic variables on the initial rate of expansion of the disease was not significant when the variables of population density and / or the date of onset of the disease were included [100º caso]. This confirmed the experience of Brazil and other countries that were in the summer period, with hot and humid weather, and suffered a severe expansion of Covid-19 – says Pedrosa.
* Trainee under the guidance of Flávia Martin