We are dealing with an increase in cases. Are we reaching the peak of the epidemic? Is it possible to predict when it will be?
The mathematical models are there and also some forecasts: those who make a parallel with China, those who do it with other epidemics, the problem is that each epidemic is different and each territory is different and responds with different measures and its own behaviours.
This is why what can be done are only sparse predictions: “It is difficult to make predictions, there are various models that are circulating, but all models presuppose assumptions, that is, some events that are predetermined, but we are in a new situation and looking at our data at the moment I don’t feel like making any predictions,” said the president of the Istituto Superiore di Sanità, Silvio Brusaferro, at a press conference on Sunday.
What are the variables that enter the calculation of the arrival of a peak? Paolo Bonanni, professor of Hygiene at the Department of Health Sciences of the University of Florence, said:
“The peak is calculated on the basis of the value of R with zero, which is the” rate of contagiousness “that for this virus we have seen is between 2.5 and 3. This means that on average each person (in a non-immune population such as ours now) infects 2 to 3 and so you can make predictions with more or less detailed mathematical models on how the epidemic curve will go with this contagion rate. This value partly depends on the biological characteristics of the virus, for example measles is much more contagious than SARS-CoV-2 and the flu is less, but not only: the density level of the population also counts, i.e. how many people meet, how long, how long.”
What is the goal?
“Vertically lower the peak, then reduce the total number of cases, but also change the arrival date and move it further: an important goal for the health system, given that the criticality increases when you cannot cope with many serious cases at the same time and since operating with a peak of many cases in a few days unfortunately also makes the value of lethality higher”.
Is the alleged seasonality of the virus one of the variables of the calculation?
“There are no scientific presuppositions, but some think that the hot season can influence the trend of the epidemic: we hope so but we have no data to confirm it for now”.
Are there any mathematical models indicating peak dates?
“The models are there, we have them, but for obvious reasons of non-alarmism and seriousness they are not disclosed, since they are projections for use by those who manage the emergency and include data that present deficiencies. We don’t know how reliable they are because we can’t know everything about this virus, the margins of error are many.”
Does the alleged peak date also depend on compliance with the restriction measures?
“What we know for sure is that the more we stick to the indications given by the government, the more we contribute to reducing the number of cases, therefore we would have fewer deaths and perhaps a slightly longer tail of the epidemic. But this does not worry us much, because the important thing is not to have the peaks all together because otherwise we question the possibility of saving people.
This is a crucial moment because the containment of the virus depends on our behaviour, if people continue to see each other despite the prohibitions they will be responsible for a significant increase in the number of cases and unfortunately also for the dead: there is truly a very strong social responsibility, MINIMISing this responsibility means increasing the chances of people dying. “
Is the epidemic over in China?
“No, it is slowing down and their measures have made it possible to block the spread. Sometimes coercion is what it takes. “
When can you really say “it’s over”, when the cases are zero?
“Yes. It can be said over when there are no more cases of a disease that has not become endemic (that is, still present in that territory). It will be necessary to see if the coronavirus will become endemic, that is, if beyond the episode with the highest peak, the disease will continue to exist in the months to come, even if in very few people and perhaps with less virulence from the clinical point of view”.
Can measures in China become less strict?
“In China now the risk is that those few who are infected will infect the susceptible, which are still very many, given that the virus is new. The measures must be kept for longer than when there is a significant drop in cases “.
Could it start all over again?
“In China, it could start all over with a re-importation of cases from areas of the world where the infection had a more delayed trend. Right now we are the danger for them. The problem in general is the non-synchrony of epidemic outbreaks worldwide. We could rest assured when we see a substantial reduction in the number of cases in other countries as well. The measures must be kept for a significantly long time to be sure that the epidemic does not resume.”
Are the healed helping to develop so-called herd immunity?
“It is still very early. We do not know how many asymptomatics are there.”