“The trend in fact is a positive evolution, of a decrease in the severity of the disease in Portugal, as expected, but this decrease is very slow”, the mathematician told Lusa.

As an explanation for the situation, the researcher from the Faculty of Sciences of the University of Lisbon pointed out that the percentage of people who have already been infected in the various age groups is very heterogeneous.

“From 20 to 29 years old, we already have 50% of the population that has been diagnosed with Covid-19, while over 60 only 17%”, he explained.

This means that the older population “was little exposed to the virus”, which means that there is still a lot of susceptibility to infection in this age group.


Therefore, he defended, “these age groups should continue to be concerned about their individual protection because they are still susceptible, despite being vaccinated”, maintaining that, if the vaccine effectiveness against infection by the SARS-CoV-2 virus is 87 %, there is a 13% probability that the person even being vaccinated will be infected.

“And if we look at the severity after a person is infected, we see that 14 people still die for every 1,000 cases over the age of 80, which is to say, if the number of cases increases in these ranges, then we have a problem, which is the increase in lethality”, he underlined.

For the researcher, risk indices must be interpreted in a “relative way” and “it is not to think that if this index tells us that we are already below the alert level, we can completely decompress and stop wearing the mask”, he defended, adding : "Risk indices are a bit blind, we have to interpret them not at the level of risk, but the evolution of that risk".