The experts Manuel Carmo Gomes and Carlos Antunes from the University of Lisbon said that the number of new cases of Covid-19 could reach 2,000 a day in the first half of December.
Experts from the University of Lisbon said that if the transmissibility index (Rt) remains above 1.1, the number of new cases of Covid-19 could reach 2,000 a day in the first half of December.
In an article published on the website of the NOVA School of Science and Technology, Manuel Carmo Gomes (epidemiologist) and Carlos Antunes (mathematician) said that the Rt has been above 1.1 and that if it remains as it is, the number of new cases should double every 30 days, and could reach 2,000 cases daily in the first half of December.
They added that in recent weeks, the ages where the risk of infection has been highest are between 18 and 25 years old, followed by children under 10 years and young adults between 25 and 40 years. These groups increased socialisation after 1 October.
They also said that there had been occasional outbreaks in homes for the elderly, stressing that this age group is not the one where cases have increased the most. Still, it has the highest risk of developing a severe illness, forcing hospitalisations and leading to death.
The experts revealed that, since the beginning of October, most new cases of infection have occurred in fully vaccinated people, stressing that the vaccines remain highly protective against severe disease but that their effectiveness against infection by the Delta variant of the virus (the dominant one in Portugal) is less than 80% and decreases over time.
“For example, data on the most administered vaccine in Portugal (Comirnaty®, Pfizer) show that in September 1.7 infections occurred per 1,000 people who had been vaccinated in July, while for those vaccinated before March, there were 3.9/1,000 infections,” they said.
They said that five to six months after vaccination, the risk of infection increases and, in the elderly or people with comorbidities, there have been cases of severe illness with hospitalisation and death.
Experts insist on the importance of booster vaccination and stress that, in the elderly, if it is fast enough, it should compensate for the decline in protection that they had obtained by vaccination at the beginning of the year, allowing them to go through the winter with a low probability of becoming seriously infected.
However, they write that the possibility of those vaccinated contracting infection suggests that any country will have great difficulty stopping the circulation of the virus entirely, even with very high vaccination coverage.
“In practice, this means that SARS-CoV-2 will probably persist among us for years to come, and many of us may have an encounter with the virus and eventually become infected,” they said.
Manuel Carmo Gomes and Carlos Antunes also recall that, since the beginning of October, the incidence of the disease has shown a persistent upward trend and warn that the persistence of an Rt above 1 leads to an exponential growth of incidence, which is likely, in a prolonged situation, to lead to higher hospitalisation rates.