Researchers from the National Institute of Health Ricardo Jorge affirm that “the trend and the magnitude” of the values of the epidemic curve in Lisbon and Vale do Tejo do not allow to conclude that it is before a second wave of covid-19.
“Since the first case of covid-19 notified in Portugal, the country remains in an epidemic situation”, however, in the region of Lisbon and Vale do Tejo (LVT) “the trend and the magnitude of the values of the epidemic curve do not allow us exclude – or conclude unequivocally – to be facing a second phase of growth “, underline researchers from the National Institute of Health Ricardo Jorge (INSA) in a written answer to questions from the Lusa agency.
According to researchers at the Department of Epidemiology at INSA, “the evolution of the current situation in LVT and other regions of the country depends on the evolution of the number of new cases, the characteristics of these new cases and the quality and speed of their control with diagnosis, testing and isolation of cases and their contacts in a few hours “.
It also depends on developments in other regions and areas, which may influence the dynamics of infection in Lisbon and the Tagus Valley. “The maintenance of transmissibility indices with values above 1 at national level (1.08 between 17-21 June) and oscillating around this value in all regions (1.13 in the North region, 1.08 in the Center region , 1.05 in the LVT region) suggests that the epidemic will probably not end in the coming weeks “, they point out.
The researchers say that the containment measures adopted led to a reduction in the rate of transmission of the infection in the community, but did not eliminate the circulation of the virus, allowing “flattening of the epidemic curve”, which is consistent with the continuous occurrence of new cases of disease over time.
“However, a moment of absence or sporadic occurrence of new cases of covid-19 per unit of time has not been reached, in any region of the country,” they state, admitting the maintenance of new cases while the high majority of the population is not find immunized.
On whether there are predictions of when the second epidemic will be, scientists say that “it is not possible to predict exactly” when it will occur, explaining that it is “an appreciable increase in the number of new cases of magnitude and geographic distribution at least identical to what occurred in the first months of this year “.
Despite the lack of knowledge about the seasonal pattern of this new coronavirus, some mathematical models predict the possibility of a second wave, but without specifying the moment of its occurrence.
However, they point out, “there is not enough information to conclude about the severity or transmissibility of the infection in the event of a second epidemic wave”.
“The greater or lesser severity and transmissibility of the infection depends on the vulnerability of the most affected groups, on possible changes in the characteristics of the virus over time and on the type and degree of implementation of the preventive measures”, explain the researchers.
They also underline that “if there is no known mutation of the new coronavirus, there is no reason to think that the characteristics of this or future increases in the incidence of covid-19 will be more aggressive”, stating that it is necessary “to evaluate the virus’s behavior as evolution “.
The researchers also report that the likelihood of new epidemic waves may be influenced by external factors that favor the spread of the virus, or by the occurrence of genetic changes in the virus that increase its transmission capacity in the human population.
“For example, other respiratory viruses, such as the flu virus, circulate with epidemic expression in the autumn and winter months, but it is not yet known whether this will be the case for SARS-CoV-2”, they add.
The researchers conclude that “the criteria for defining a second epidemic wave of covid-19 are not yet consensual in the world, which increases the complexity of interpreting epidemiological data and indicators, compounded by the effects of human intervention on the natural history of the disease. “.
They stress, however, that “the essential thing is to focus the discussion on the risk of infection and its components, determining factors and feasible control measures, from the outset prevention”.
Portugal accounts for at least 1,555 deaths associated with covid-19 in 40,866 confirmed cases of infection, according to the latest bulletin from the Directorate-General for Health (DGS).
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