"The Delta variant (B.1.617.2) has a relative frequency of 99.7% in the week of 30 August to 5 September, remaining dominant in all regions, according to data collected to date" , indicates the weekly report on the genetic diversity of the new coronavirus by the National Institute of Health Doctor Ricardo Jorge (INSA).

Of the total Delta sequences already analysed by INSA, 66 had an additional mutation in the `spike' protein, a sublineage known as 'Delta Plus' that has “maintained a relative frequency below 1%” since June.

Regarding the Gamma variant, after three weeks without detection of any cases in random sampling, one case was detected in the week of 30 August to 5 September in the region of Lisbon and Vale do Tejo, the report states, which also states that no cases of the Beta variant were detected.

As for Alpha, initially associated with the United Kingdom and which became predominant in Portugal, there are still no cases recorded in the last four weeks.

These four variants - Delta, Gamma, Beta and Alpha - are classified by the World Health Organization (WHO) as of concern (VOC - Variant of Concern), because they can be more transmissible, cause greater severity 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 gene sequences of the SARS-CoV-2 coronavirus per week have been analysed since the beginning of June, from samples collected randomly in laboratories in the 18 districts of Mainland Portugal and the autonomous regions of the Azores and Madeira, covering an average of 126 municipalities 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.