It is exactly this “flattening” of the curve that leads health and political authorities to admit, without certainty, that the peak of the outbreak initially forecast for mid-April or even for May may have already happened or is now happening. The hypothesis that the peak was already passed in March was raised by health experts Tuesday, at the experts’ meeting with politicians and social partners. This Wednesday, Graça Freitas admitted that the growth of the outbreak may be in the “plateau” phase, that is, stabilizing the “peak” of the pandemic, but he warned that this “is not a guaranteed fact” and that it is early to draw conclusions. In fact, everyone has been very restrained in celebrating the low and regular numbers of the past few days, with a daily rise in cases between 5% and 6% on average.
After this further analysis made for the Observer, the professor of Public Health and Epidemiology at Universidade Nova de Lisboa, Inês Fronteira also considers “Too early” to conclude definitively that the evolutionary curve of new cases has stabilized even definitively. But he says that “there is a tendency for the number of new cases to be very similar from day to day, there is not much variation” and “if there is not much variation we can expect that the curve ahead looks more like a plateau than the a peak”.
Looking at the evolution of infection cases confirmed daily by the health authorities, in the last days of the analyzed period – 25 days, starting on March 13, the day when it is considered as the beginning of the community transmission of the virus – “Oscillations” have all been “below a thousand cases” and “are not major oscillations”, explains the expert. “So, maybe in the next few days we can expect this trend to continue, that we are on that plateau. Still, we must specify that we cannot complete this for now. You have to let a few more days pass to see if this trend continues ”.
The data do not allow us to be certain that the pandemic is in the process of being overcome, not least because the evolution of Covid-19 in each country remains unknown – because it depends on too many behavioral and socio-political factors adopted to mitigate the spread . However, there is some concrete data: in the 25 days after the detection of the first case of local transmission, between residents, of the new coronavirus in China, South Korea, Italy, Spain, Portugal, Germany, France and the USA, the country that showed more stability and less peaks and daily increases in the evolution of the number of new cases was Portugal.
As Inês Fronteira explains, when the “flattening coefficient” – which “describes the finding of the curve” of new cases of infection reported daily – is less than 0, it is said that the curve is flattened. If the value is positive, “the curve is more pointed (leptocurtic)”, in which case there are greater oscillations and increases in confirmed infections each day.
The flattening coefficient calculated by the epidemiologist for Portugal for the 25-day period that started on March 13 (moment of detection of the first case of local transmission) is -1,395. A value that is lower than that recorded in the 25 days following the detection of the first case of local transmission in countries such as China (-1.1752), South Korea (-0.761), Italy (-0.362), Germany (0.377), Spain (2.130), France (5,725) and the United States (19,477).