“It is estimated that the BA.2 lineage is clearly dominant in Portugal, representing 82% of the positive samples on March 14th”, advances the weekly report on the genetic diversity of SARS-CoV-2 by the Instituto Nacional de Saúde Doutor Ricardo George (INSA).
The BA.2 lineage, which shares several genetic characteristics with BA.1, was detected in Portugal at the end of 2021 and has been increasing in prevalence since then.
Classified by the World Health Organization (WHO) as “of concern”, the Omicron variant encompasses several lineages identified by the prefix `BA´, including BA.1 and BA.2, which descend from the same ancestral lineage (B.1.1. 529) and have an “excess” of mutations in the protein `spike´.
As for BA.1, identified for the first time in Portugal in November 2021 and which reached a maximum prevalence of 95.6% of infections in January, the downward trend of recent weeks continues, now dropping to 18%, advances the INSA.
Recently, the WHO advanced that preliminary studies suggest that BA.2 is more transmissible than BA.1, but the organization noted that the 'real world' data on clinical severity in South Africa, the United Kingdom and Denmark, where immunity from vaccination and natural infection is high, indicate that “there was no reported difference in severity between BA.2 and BA.1”.
“Reinfection with BA.2 following infection with BA.1 has been documented, but initial data from population-level studies suggest that infection with BA.1 provides strong protection against reinfection with BA.2,” added WHO.