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Home » XBB.1.5 COVID-19 variant — here comes the Kraken FAQ

XBB.1.5 COVID-19 variant — here comes the Kraken FAQ

Last updated on February 7th, 2023 at 02:31 pm

The pandemic that keeps on giving has given us a new COVID-19 variant to worry about — XBB.1.5, also known as the Kraken.

As we approach the third anniversary of the pandemic (remember when we thought it would be done by Summer, 2020?), many people are weary of reading anything new about the disease. It’s like our brains have become “immune” to new information about this disease. But XBB.1.5 should be a variant that you should follow because it has evolved in a way that might make it more dangerous for the population.

This post will just try to give you the best information we have about the variant, some of it concerning, and some of it just newsworthy.

vaccine bottle in close up photography
Photo by Maksim Goncharenok on

What is the XBB.1.5 variant?

XBB is a descendant (one of at least 300) of the original Omicron strain of the SARS-CoV-2CoV-2 virus which arose in late 2021. These new strains appear to originate from genetic drift, something we see with the influenza viruses. Of course, this kind of drift occurs over a few years with the flu but is crammed into a handful of months with COVID-19.

XBB hit Singapore in the fall of 2022, causing daily cases to go from 4,700 on 9 October to 11,700 on 10 October, a massive increase.

XBB.1.5, sometimes called the Kraken variant evolved from XBB.1, which evolved from XBB — an Omicron subvariant that emerged in India in mid-August and quickly became predominant there, as well as in Singapore and other regions in Asia, according to a December 2022 paper in Cell.

The CDC reports that the new variant wa% of new COVID-19 cases in the USA as of 7 January 2023.

Virologist Jesse Bloom, PhD., of Fred Hutchinson Cancer Center in Seattle, claims that XBB.1.5 evolved from the recombination of two descendants of the BA.2 variant.

The evolution of SARS-CoV-2 is complex beyond almost any other virus that we have encountered. Although I am not a virologist, nor play one on the internet, I am very concerned that COVID-19 variants are going to be attacking us for years until we get a vaccine that recognizes the more conservative parts of the virus, ones that rarely mutate. Or we may have to accept that COVID-19 is a chronic disease like the common cold albeit infinitely more deadly and dangerous.

The XBB.1.5 FAQ

Is this variant more dangerous than other COVID-19 variants?

The evidence suggests that the XBB.1.5 variant does not cause more severe illness than other Omicron subvariants, as there hasn’t been a greater increase in hospitalizations in regions hit hardest by the strain. This is somewhat good news.

Is XBB.1.5 more transmissible than other variants?

It appears that it is. The variant has a higher affinity than other variants for the ACE2 enzyme, which is found on the membranes of various cells in the body. If the virus can attach to the ACE2 on the cell easier then it can infect the cell easier.

Does XBB.1.5 avoid the antibodies produced by previous infections or vaccines?

According to a December 2022 paper published in Nature, the variant is equally as immune evasive as the two other XBB lineages. Driving that higher affinity for ACE2 is a change at site 486, which has been a “major site of antibody escape going back to the earliest variants,” according to Dr. Bloom.

Above is the technical explanation of the mutations that cause higher transmissibility and higher antibody escape.

What about vaccines (including boosters) or prior infection?

We don’t have a lot of information yet, but an article in Scientific American said:

While the subvariant may, to some extent, dodge antibodies conferred by vaccines or prior exposure, it will not skirt the immune system completely, says Alessandro Sette, a professor at the La Jolla Institute for Immunology. Sette says XBB.1.5 would have a hard time escaping the cellular immunity conferred by killer T cells, which work by destroying virus-infected cells even if antibodies fail to stop those cells from being infected in the first place. This T cell response helps prevent severe disease.

Even though vaccines may not prevent one (or even more) infections from COVID-19, they significantly reduce the risk of hospitalization or death from the variants and subvariants. We expect the same with the Kraken variant.

If you got a bivalent booster when it was first available, should you be considering another booster now?

There is no guidance yet for if or when a second bivalent booster would be recommended. As of now, about 15.4% of eligible individuals have received their bivalent booster, so I would say the more pressing concern is to increase vaccine booster uptake. 

Is Paxlovid still effective?

We don’t know for sure, as we need more data. However, there is no reason to doubt that it will be just as effective against the new variant as it is for Omicron and other variants.

Why is it called the Kraken variant?

The new XBB.1.5 variant has been dubbed the Kraken variant across social media. The name was invented by biology professor T. Ryan Gregory of the University of Guelph in Canada. Apparently, Gregory wanted to give this subvariant a name with more panache than XBB.1.5 or even Omicron to better communicate information about variants to the public. It is much easier to say than its scientific name, and I’m all for better scientific communication.


I’m sure as more information and data are gathered about this Kraken variant, we will try to communicate it to you, the loyal readers. But for now, we’re early in this new phase of the pandemic and predictions are difficult. Let’s hope for the best.

But for now, get the COVID-19 vaccine and get fully boosted. This appears to be the only sure-fire way to reduce your risk of hospitalization and death from COVID-19. Vaccines save lives.


Michael Simpson

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