Covid changes its face and does its job as a virus, that is, mutating to survive. JN.1, the latest dominant variant of the Sars-CoV-2 virus, has been evolving for some time, giving rise to subvariants with additional mutations nicknamed Flirt, capable of spreading more quickly. One in particular is racing: it’s called KP.2 and it’s under the spotlight […]
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Covid changes its face and does its job as a virus, that is, mutating to survive. JN.1, the latest dominant variant of the Sars-CoV-2 virus, has been evolving for some time, giving rise to subvariants with additional mutations nicknamed Flirt, capable of spreading more quickly. One in particular is running: it’s called KP.2 and is under the spotlight of experts. In the United States, in fact, this “daughter” of JN.1 has surpassed its “mother”. According to the latest data from Centers for Disease Control and Prevention (Cdc), it is now responsible for one in four infections (24.9% versus 22% from JN.1). The spread was rapid.” and the rate of KP.2 infections “reached 20% in the UK in early April“, suggesting that it has the numbers to “become globally predominant”. The authors of a preliminary study published on the pre-print platform explain thisbioRxiv‘, which does not submit to audit, which indicates that KP.2 is “more transmissible and immunoevasive” of JN.1 or escapes the vaccine.
“The rapid emergence and diversification of the JN.1 variant and its descendant KP.2, which shows significant mutations in the structure of the Spike protein and increased resistance to existing vaccines, highlight the need for further research to understand the implications” of the new Flirt variant “for public health and vaccine development.” This is the premise of the scientists coordinated by Kei Sato of the University of Tokyo in Japan, who analyzed 30 KP.2 genomic sequences from the United States, UK and Canada. Using specific models they then calculated the transmissibility index Re (effective reproduction rate, i.e. the average number of people that an infected person infects) of the new variant, and with virological tests they evaluated its infectivity and immune evasion.
The researchers concluded that KP.2 exhibits “significantly improved epidemiological fitness compared to its predecessors, including the XBB lineage. This is confirmed by the estimated Re for KP.2 in the USA, UK and Canada, respectively 1.22, 1.32 and 1.26 times higher than that of JN.1″. Despite the greater transmissibility, “the infectivity of KP.2 was significantly lower (10.5 times) compared to that of JN.1”, an element which according to the authors could suggest “different mechanisms or routes” through which the new variant spreads and establishes itself in the host. KP.2 ultimately showed “significant” immune escape capacity, with “a 3.1-fold reduction in susceptibility to neutralization by sera from individuals vaccinated” with monovalent anti-XBB.1.5 vaccines “without prior infection, and by 1.8 times from sera from people with previous infections.” For scientists “this greater resistance could partly explain the higher Re of KP.2, indicating a greater ability to evade immune responses compared to JN.1 and other previous variants.”
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