“Since December 6, there has been a high growth in the proportion of probable cases of the Omicron variant, reaching an estimated proportion of 93.2% on January 10”, says the report by the National Institute of Health Doutor Ricardo Jorge (INSA) on the genetic diversity of SARS-CoV-2.
On January 3, Omicron had already reached a frequency of 89.6% of cases of infections registered in the country.
According to the institute that monitors the evolution of this coronavirus in Portugal, Omicron’s “abrupt increase in community circulation” parallels the scenario observed in countries such as the United Kingdom and Denmark.
According to INSA, this variant was detected for the first time in Portugal in the week of 22 to 28 November, having registered a “galloping growth in circulation during the month of December”.
“The sequencing data still show considerable heterogeneity in regional terms”, indicating that the number and timing of introductions, as well as the beginning of wider community circulation, occurred differently in the various regions of the country.
“In fact, community circulation of the Omicron variant occurred earlier and more intensely in the Lisbon and Tagus Valley region, having become dominant about one to two weeks earlier than in the other regions,” the report added.
Regarding Delta, the variant that was predominant in Portugal for several months, “its relative frequency has been decreasing since the week of November 22nd to 28th as a result of the abrupt increase in circulation of the Omicron variant.
“Among the various sublines of the Delta variant still in circulation, the AY.4.2 lineage stands out, which, in the week of December 27, 2021 to January 2, 2022, still had considerable circulation in the Algarve”, said the INSA.
As part of the ongoing monitoring of the genetic diversity of SARS-CoV-2, an average of 527 sequences per week have been analyzed since the beginning of June 2021.
These sequences were obtained from samples collected at random in laboratories spread over the 18 districts of mainland Portugal and the autonomous regions of the Azores and Madeira, covering an average of 132 municipalities per week.