“The five countries that reported the highest prevalence of BQ.1 are Ecuador (65.5%), Portugal (56.7%), Spain (54.1%), France (48.7%), and Colombia ( 46.8%)”, said the WHO in the weekly epidemiological update of Covid-19.

The report states that the emergence of new waves of infection is dependent on regional immunity, the size of previous waves of contagion, and vaccination coverage.

"While further studies are needed, current data does not suggest that there are substantial differences in disease severity" for various circulating Omicron strains, including BQ.1, the document notes.

According to the WHO, BQ.1, including its descendants such as BQ.1.1, “is one of the fastest growing strains” globally and has spread to 90 countries, with a prevalence of 33.9%.

According to the update, the evolution of the Ómicron variant continues to show a genetic diversification that has already resulted in more than 540 descendant lines and 61 recombinants.

Five sublines of Ómicron, including BQ.1, "are under monitoring due to their relevant genetic alteration, the increase in prevalence and the observed and continued impact on the incidence of cases in more than one country", advanced the WHO.