“The Delta variant (B.1.617.2) has a relative frequency of 100% in the week of August 16th to 22nd in all regions, according to data collected to date”, states the INSA.

According to the institute, the various variants that have already circulated in the country - among which Beta, Gama and Alpha, which was the predominant one - have a prevalence of 0%, which means that no cases of these strains were detected in the last few weeks.

As for Delta, initially identified in India and considered more transmissible than Alpha, of the total analysed sequences of this variant, 66 showed an additional mutation in the `spike' protein, an underline known as Delta Plus which has “maintained a relative frequency below 1 percent” in recent weeks.

As part of the continuous monitoring of the genetic diversity of SARS-CoV-2, the INSA has analysed a weekly average of 559 sequences, obtained from samples collected at random in laboratories distributed throughout the 18 districts of mainland Portugal and the autonomous regions of the Azores and Madeira, covering an average of 123 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.