The World Health Organization (WHO) has classified the JN.1 variant of the covid virus as a variant of interest “due to its rapidly increasing expansion,” as reported today in a statement.
The health organization warns that “with the arrival of winter in the northern hemisphere, JN.1 could increase the burden of respiratory infections in many countries.” Even so, “the risk to global public health is assessed as low at the current time (...) based on available data.”
The JN.1 variant is demonstrating a greater contagion capacity than any previous variant thanks to a specific mutation that affects the S protein of the coronavirus. This is the protein that antibodies recognize and, thanks to the L455S mutation, the variant can more easily slip past the antibody attack. But JN.1 has not shown the ability to cause a more severe infection than previous variants.
The WHO highlights that “current vaccines continue to protect against severe illness and death from JN.1 and other circulating variants of SARS-CoV-2, the virus that causes covid.” However, the protection offered by vaccines against contagion is low if several months have passed since the last immunization. Therefore, an increase in infections can be expected in the coming weeks.
This trend is already noted in Catalonia, where covid has become the most frequent respiratory infection in the last week, coinciding with the emergence of the JN.1 variant and the drop in temperatures. According to data updated yesterday by the Information System for Infection Surveillance in Catalonia (SIVIC), the number of people hospitalized with covid (but not necessarily due to covid) has increased by 20% in one week.
The JN.1 variant represented more than 20% of the samples analyzed in Catalonia last week, when three weeks before it did not reach 5%. In Denmark, the country that sequences circulating variants most comprehensively, it represents more than 50% since the end of November. It is rapidly expanding throughout Europe, North America, China, Japan, Australia and New Zealand, according to epidemiological surveillance data from the Scripps Research Institute in California. “It has become dominant on a global scale,” says Eric Topol, director of the Scripps Institute.
JN.1 is part of the lineage of omicron variants, which are characterized by high contagiousness and a low risk of serious complications in immunized people. The omicron lineage has become hegemonic on a global scale and represents practically 100% of the SARS-CoV-2 samples that are detected.
Within the different branches of omicron, JN.1 is a descendant of the BA.2.86 variant, which was detected for the first time in August and which surprised virologists because it had more than 40 new mutations compared to the XBB.1.5 variant, which At that time it was dominant. Of these mutations, 34 modify the S protein of the virus, which is the protein it uses to attach to human cells and also the protein that antibodies recognize. Therefore, it was feared that the BA.2.86 variant had a greater ability to bind to cells and/or hide from antibodies.
Now, the JN.1 variant adds an additional mutation called L455B. This mutation is the key to its greater contagion capacity, according to research by virologist Yunlong Cao, from Peking University, published on December 15 in The Lancet Infectious Diseases. Research shows that L455B gives the virus a superior immune evasion capacity.
