The evolution of the models, the parameters that have been taken into account and the particularities used to make predictions were explained by Dr. Raúl Guinovart Díaz, dean of the Faculty of Mathematics and Computing at the University of Havana.
In addition, it valued the relationship between vaccination and the care to be followed after this process to definitively defeat the pandemic, and gave a close prognosis and another in the longer term.
Guinovart Díaz presented the design of a “compartment model with vaccination”. “As in most mathematical models, what we do is divide the population into states, in a position with respect to the epidemic. To simplify, we have considered susceptible cases (it would be the entire population), such as those who have already acquired the virus, or those who have recovered and are now convalescing, and we have also added three parameters that allow a better analysis of the situation and to to be able to evaluate the impact of vaccination ”.
For example, an Alpha parameter was introduced that represents the speed or ability of people to protect themselves and maintain protective measures such as the use of the face mask, washing their hands, distancing themselves and even staying in the house if possible.
Another parameter is the speed of vaccination. “There is another group of people that we can also protect by vaccinating,” which is developed in Cuba through a vaccination program that allows people to be protected against this virus.
“The faster the vaccination, the better we will have results and the faster we will achieve the immunization of the population. What we want is one thing and reality is another, because you have to develop vaccines, evaluate them, be sure that they really have high efficacy and then produce them and vaccinate the entire population. “
What can we see in that scheme? “We see that people protect themselves and are vaccinated, but here is a detail, the fundamental way in which the pandemic is transmitted is through the contact of infected people, and of course through surfaces that a person has touched.”
The dean of the Faculty of Mathematics and Computing at the University of Havana commented that in the new group called “protected and vaccinated” in the scheme, people are likely to get sick.
That probability is given, he argued, because the vaccine is not 100% effective, even the immune response varies from one person to another, depending on the age and the comorbidities they suffer.
He specified that the beta parameter that appears in the diagram is that of transmission. “No matter how low the ineffectiveness of the vaccine, no matter how much we protect ourselves, if there is a lot of transmission, the probability that we will get sick or that we get infected when we come in contact with a sick person, also increases.”
This scheme, he added, is translated into systems of differential equations and the models have several steps, but the fundamental ones are the formulation of the problem, the estimation of the parameters – carried out by certain optimization, statistical and probabilistic processes – and the solution of these. equations.
One of the most important variables is the transmission coefficient. “It is the one that tells us with what speed the virus is transmitted and is closely related to the reproductive number. We have introduced three new variables, which are not estimated: the alpha parameter (the speed of protection), the vaccination and the efficacy of the vaccine that appears in the last equation ”.
“What we want is to illustrate how these variables act and how we have to protect ourselves regardless of whether there is a vaccination process, with a certain rhythm.”
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