The weekly report on the genetic diversity of the new coronavirus by the National Institute of Health Doctor Ricardo Jorge (INSA) indicates that the Delta variant, originating in India and considered to be most transmissible, has a “relative frequency of 100% in the week of September 6th to 12th in all regions” of the country.
According to the document, of the total analysed sequences of this variant to date, 66 had an additional mutation in the `spike' protein, a sublineage known as 'Delta Plus', but no cases have been reported in recent weeks.
Regarding the Gamma variant, associated with Brazil, after three weeks without being detected in the analysed samples, two unrelated cases were recorded in the regions of the Alentejo and Lisbon and Vale do Tejo in the week between August 30th and September 5th.
The Alpha variant, originating in the United Kingdom and which became prevalent in Portugal, has ceased to be in circulation for the last five weeks, according to data from the INSA.
Delta, Gamma, Beta and Alpha are classified by the World Health Organization (WHO) as Variants of Concern (VOC) because they can be more transmissible, cause more seriousness of disease or have characteristics that allow the evasion of the immune system, with potential reduction in the effectiveness of vaccines.
As part of the continuous monitoring of the genetic diversity of SARS-CoV-2, an average of 552 sequences per week has been analysed since the beginning of June, from samples collected at random in laboratories in the 18 districts of mainland Portugal and the Azores and Madeira, covering an average of 128 counties per week.
In June, the institute announced a strengthening of surveillance of the variants of the virus that causes covid-19 in circulation in Portugal, through its continuous monitoring.
According to the INSA, this strategy allowed for a better genetic characterization of SARS-CoV-2, since the data are analysed continuously, and there are no longer time intervals between analyses, which were essentially dedicated to specific studies of genetic characterisation requested by the public health.