Brazil reduced Covid-19's expansion rate from 3.5 to 1.4, but value is still high

The Covid-19 'basic breeding number' -- a parameter that indicates how many people an infected individual has infected -- has fallen in Brazil since the beginning of the pandemic, but is still high. When the new coronavirus arrived in the country on February 26, each person who contracted it passed the disease to another 3.5, on average. After the first measures of social isolation, on March 23, the number dropped to 1.9. Now, with more states promoting quarantine, it's at 1.4. That is, each two infected Brazilians transmit Sars-CoV-2 to three others. The value is lower, but still worrisome, because it feeds an exponential growth of the pandemic, which doubles in size every 9 or 10 days, a reckless level at a time when Brazil already has more than 260,000 cases. The researchers responsible for the estimate are nuclear physicist Rubens Lichtenthäler Filho, a professor at the University of São Paulo (USP), and his son, Daniel, a physician at the Hospital Israelita Albert Einstein. Behind the numbers: Covid-19 took brilliant minds from Brazil and the world To get to the numbers, the two worked essentially with official data. They claim that the key dates identified in the analysis coincide with times when states have implemented tougher isolation measures. "We know that the impact we are seeing is progressive measures of social distancing over time," says Daniel. To see a clearer picture of the evolution of the pandemic, Daniel explains that official data were treated to eliminate statistical fluctuations (on Sundays there are few records, for example) and was taken into account the time of the disease and its incubation period. The mathematical treatment of work used resources commonly used in rubens' area of activity.