Since the start of the Covid pandemic and the emergence of new variants of the original virus, each that has prevailed has become “the most contagious”. Alpha was much more contagious than the original but less so than Beta, which in turn had less transmission capacity than Delta, very contagious but not as contagious as Omicron. In this evolution, the last step (for now) is XBB.1.5, a subline of Omicron unofficially christened as the Kraken, which is advancing across the United States and has once again taken over the gang of those most easily infected, although it is no more serious seems to be.
XBB, a fusion of two Omicron variants, has been under the World Health Organization (WHO) radar since early December. Two mutations of these have resulted in XBB.1.5, which has become the world’s leading candidate after growing rapidly in the US, where XBB and its progeny account for nearly half of cases.
The WHO has already detected it in 25 countries, including Spain, where some cases have been identified, albeit anecdotally for now. A clear predominance of BA.4 and BA.5, which have been massively infecting since the summer, was found both in the sequenced random samples and in the wastewater analyzes of the Ministry of Health.
The nature of the virus means that in order for a variant to become predominant, it must be more contagious than the previous ones. Otherwise, it would not be imposed on those already in circulation. But the transmission capacity of a virus is not an absolute and isolated fact, but the result of the interaction with its hosts (people), their immune status and the interactions between the two.
Since the proliferation of vaccines, none of the SARS-CoV-2 variants have proven more serious than the previous one. There has not been one that has so eluded the immune system that it causes a greater proportion of deaths or hospitalizations in a population with more immunity generated both by injections and naturally by infection. And right now, XBB.1.5 seems to be no exception.
However, if a variant causes very many infections, statistically it also increases the number of people who become seriously ill or die, even if it is much less deadly than the previous ones. Despite this, the waves have caused fewer and fewer hospitalizations in Spain since vaccination began.
This confirms that the variants are becoming milder: even with millions of infections (some studies estimate more than 12 million in Spain alone in the seventh wave), they are not able to strain the capacity of intensive care units, although they cause death from Hundreds of people, especially very old and vulnerable people who suffered from other diseases and whom the Covid manages to decompensate them for good.
For this reason, health authorities strongly advise those over 60 to get the second booster shot, which protects against Omicron variants more effectively than the previous ones. In Spain, vaccination numbers have been stagnating for weeks: just over half of the elderly population have received them.
For technical reasons, the omicron was the last to be officially christened with a Greek letter. All others were sub-lines, only responsive to letters and numbers, sometimes given improvised nicknames for identification, with names such as Centaur, Hellhound, or Nightmare, the first nickname lengthened for the XBB variant.
Kraken, which refers to a sea monster from Scandinavian mythology, was the brainchild of Ryan Gregory, a biology professor at the University of Guelph (Ontario, Canada), who is trying to make information about the new variants more accessible. So replace a name like this with a number. It so happens, however, that these new bloodlines, conspicuously named, are usually neither as hellish, nor as nightmare-like, nor as monstrous as their name might suggest. Of the hundreds of variants that have circulated and the dozens that have been identified as a threat, few have caught on, and in less and less virulent ways.
The WHO warns that the more infections occur, the more likely it is that the virus will mutate and escape the immune system. It is an inherent risk of every virus: that it will eventually become more deadly, as is the case with the flu, which has caused major epidemics throughout history.