EG.5 is a family of Omicron variants (descended from XBB.1.9.2) that first appeared back in February 2023. The World Health Organisation (WHO) classified it as a “variant under monitoring” on July 19 after a surge in COVID infections from early July. It has been increasingly reported across the globe, particularly in Asia. On 9 August 2023, it was upgraded to a “variant of interest”.
Is Eris different to other variants?
At this stage, there is no evidence EG.5.1 causes more severe disease than other Omicron variants, and it seems to cause similar symptoms. How this virus enters cells and tissues in our body is also similar to XBB.1.5 (sometimes referred to as Kraken) and other Omicron variants. While the severity of the illness it causes will need to be documented carefully, there are no indications it’s different from XBB.1.5. The virus has changed, incrementally, making EG.5.1 more transmissible. While this enables it to compete with other circulating variants.
How WHO define Eris ?
The WHO defines a variant of interest as one that has genetic changes that could increase its transmissibility, virulence, its ability to evade vaccines, be treated with drugs or detected via current testing methods – as well as already demonstrating a “growth advantage” over other circulating variants. Yet, another XBB variant that has been around since February and dominated over our autumn-winter peak in Australia, XBB 1.9, has remained on the WHO’s lesser “variants under monitoring” list.
Will vaccines protect against it?
EG.5.1 has two important additional mutations that XBB.1.9.2 does not have: F456L and Q52H, whereas EG.5 only has F456L. The extra small change in EG.5.1, the Q52H mutation in the spike protein, is enough to give EG.5.1 an edge over EG.5 in transmissibility. The good news is the bivalent vaccine antibody responses to EG.5.1 are similar to those for variants that dominated earlier in the year in Australia.
Will Eris prompt a rise in COVID cases?
Given the ancestral variant for EG.5.1 is XBB 1.9, which was our dominant variant over winter, it’s also possible we might have better population level immunity than countries like the US. As we start to emerge from our winter, with boosted natural immunity and booster vaccination, we may be less likely to see this EG.5.1 muscle out other variants. However, as our immunity wanes, with greater distance since our last wave, we will inevitably see infection rates start to push up again – potentially in late spring.
