The data on coronavirus which are disseminated daily about new infected people are important but must be read correctly.
The trend of the curve, which records the increase in cases with the passing of the days, is influenced by two aspects almost always overlooked. The first concerns the number of swabs carried out day by day: the higher this value is, the more the infected increase, considering and considering that the submerged cases amount, according to experts, to several thousand units.
The second aspect is purely practical. The tests carried out need to be analyzed. The analysis laboratories, while working at full speed, can examine more once than another, thus giving the impression that the infections can be decreased or increased. In short, the deeper you dig, the sicker you are.
In this regard, Paolo Grossi, professor of infectious diseases at the University of Insubria in Varese and a member of the permanent working group on coronavirus of the Superior Health Council, explained to the Corriere della Sera it matters to consider the trends of the curve and not the data recorded a single day.
The changes in the epidemiological curve, on the contrary, rarely depend on the number of people infected by the asymptomatic, considering that “their rate of contagiousness, according to current knowledge, is minimal“.
The analysis of the trend
The emblematic example is the Lombardy. Last Thursday, 6,047 swabs were made in the region, 4,971 the day before and 3,452 the day before. Between Wednesday and Thursday we had to deal with a 12% increase in new cases. Because “the results of a single day are not significant. The trend must be examined“, Explains Professor Grossi.
From this point of view it is useful to compare the last two weeks. In Milan, the growth of infections passes from an average of 17% to 9%. The same goes for Brescia (from 13% to 6%) and Bergamo (from 8% to 6%). There was a slowdown of the spread of the virus even if, underlines Grossi, “giving up on containment measures would be a serious imprudence“.
However, Grossi believes that one mass screening on the population, as requested by many, it makes little sense. The prof is lapidary: “The swab may be negative one day and positive the next because the virus was simply still incubating. This could give false assurances, while it is important that everyone stays at home regardless. It is the only real solution to counter the spread of the virus“.
But then, if it is not the daily numbers that count (but, as mentioned, the trend of the curve), it makes sense that the authorities communicate the data? “I – concluded Grossi – I find it correct that the authorities communicate them transparently day by day, after which the population must understand that the results of a single day are not significant“.
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