Why this ‘new-look’ COVID variant signals a new phase of the pandemic – SBS News

Since it was detected in August 2023, the JN.1 variant of COVID has spread widely. It has become dominant in Australia and , driving the biggest COVID wave seen in many jurisdictions for at least the past year. The World Health Organization (WHO) and in January strongly stated COVID was a continuing global health threat causing "far too much" preventable disease with worrying potential for long-term health consequences. JN.1 is significant. First as a pathogen it's a surprisingly new-look version of SARS-CoV-2 (the virus that causes COVID) and is rapidly displacing other circulating strains ( ). It's also significant because of what it says about COVID's evolution. Normally, SARS-CoV-2 variants look quite similar to what was there before, accumulating just a few mutations at a time that give the virus a meaningful advantage over its parent. However, occasionally, as was the case when Omicron (B.1.1.529) arose two years ago, variants emerge seemingly out of the blue that have markedly different characteristics to what was there before. This has significant implications for disease and transmission. Until now, it wasn't clear this "step-change" evolution would happen again, especially given the ongoing success of the steadily evolving Omicron variants. JN.1 is so distinct and that many are wondering whether the WHO will recognise JN.1 as the next variant of concern with its own Greek letter. In any case, with JN.1 we've entered a new phase of the pandemic. Where did JN.1 come from? The JN.1 (or BA.2.86.1.1) story begins with the emergence of its parent lineage BA.2.86 around mid-2023, which originated from a much earlier (2022) Omicron sub-variant BA.2.

Chronic infections that may linger unresolved for months (if not years, in some people) likely play a role in the emergence of these step-change variants.

Updated monovalent vaccines, tests and treatments remain effective against JN.1. Source: AAP / Wolfgang Kumm/DPA

The sheer volume of infections occurring globally sets the scene for major viral evolution. SARS-CoV-2 continues to have a very high rate of mutation. Accordingly, JN.1 itself is already mutating and evolving quickly.

The first relates to how the virus evades immunity. JN.1 has inherited more than 30 mutations in its spike protein. It also acquired a new mutation, L455S, which further decreases the ability of antibodies (one part of the immune systems protective response) to bind to the virus and prevent infection.

Whatever the case, these findings show JN.1 (and SARS-CoV-2 in general) can not only navigate its way around our immune system, but is finding new ways to infect cells and transmit effectively. We need to further study how this plays out in people and how it affects clinical outcomes.

There are two elements to "severity": first if it is more "intrinsically" severe (worse illness with an infection in the absence of any immunity) and second if the virus has greater transmission, causing greater illness and deaths, simply because it infects more people. The latter is certainly the case with JN.1.

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Why this 'new-look' COVID variant signals a new phase of the pandemic - SBS News