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The ‘Kraken’ variant spreads quickly and is already the majority in Spain

In early January, a new Omicron subvariant, XBB.1.5, better known as ‘Kraken’, attracted the attention of the World Health Organization (WHO). Detected in the United States, in a short space of time, it spread to more than twenty countries. The director general of the WHO himself, Tedros Adhanom Ghebreyesus, pointed out that the international health organization was closely monitoring and evaluating the risk of this subvariant. Spain did not take long to register the first cases and now, in less than two months, it represents 40% of Covid-19 infections in the country, according to the report ‘Update on the epidemiological situation of SARS-CoV-2 variants in Spain’, published last Monday, March 6.

In addition to being the predominant one in Spain, its capacity for expansion stands out, since the percentage of reported cases of this sublineage has gone from 9.7% to 40% in just one month. The rest of the infections are completed at the national level with those derived from Ómicron BQ.1 (including BQ.1.1), which stands at 35.6% and those derived from BA.2.75, 13.3% (of which , CH.1.1 represents 11.1 percent of the variants analyzed).

The Health report points out that XBB.1.5 is the variant that “is experiencing the greatest expansion globally” and Spain is no exception. The explanation would be that “this lineage presents a mutation that gives it the ability to evade the response to antibodies that were already present in XBB or XBB.1, but affects binding to the ACE2 receptor to a lesser degree, which could imply a greater transmission capacity compared to XBB and XBB.1”, as detailed by the Ministry’s technicians.

However, in the last Emergency Committee of the International Health Regulations on the coronavirus (COVID-19) pandemic of the WHO, held at the end of January, it was recognized that, although the sublineages of the Omicron variant currently circulating in everyone is highly transmissible, it has been detected that the disease is less severe compared to previous variants of concern, mainly due to the immunity generated in the world population both through vaccination and naturally.

Although the Omicron sublineages that currently circulate are highly transmissible, the disease is less severe.

Even so, the WHO continues to show its concern and warns that we must continue to be vigilant because Covid continues to cause “a still high number of deaths compared to other respiratory infectious diseases”, in a panorama with “insufficient adoption of vaccination in countries low and middle income, as well as in the highest risk groups worldwide” and with the uncertainty regarding the appearance of new variants of the coronavirus with a greater capacity to violate the immunity of vaccines.

Therefore, the expert committee expressed the need to improve surveillance and reporting of hospitalizations, admissions to intensive care units and deaths, “to better understand the current effect of Covid-19 on health systems and determine appropriately the clinical characteristics of the disease and the condition following it.

What is known about the ‘Kraken’ XBB.1.5 subvariant?

It is a new mutation of Ómicron, the most contagious Covid variant so far, and comes from another variant, XBB, detected for the first time in October last year, and which is in turn a recombination of two other subvariants of Ómicron .

Like the previous ones, XBB.1.5 stands out for its high infectious capacity. The European Center for Disease Control and Prevention (ECDC) estimates that this lineage has a large growth advantage relative to lineages previously circulating in North America (109%) and Europe (113%). .

According to this organization, the most likely explanation for the growth advantage is found in the already high level of immune escape demonstrated by XBB, from which it comes, combined with the effect of the S486P mutation. “This mutation has been rare earlier during the pandemic, probably because it requires two nucleotide substitutions in the same codon to change from phenylalanine to proline. In fact, other variants with this change have emerged before without being successful,” he points out.