EXPERT REACTION: How will new COVID-19 subvariant Eris impact Australia?

New variants are expected and will continue to arise with time as the virus replicates through human populations. The current EG.5 strain is a new circulating variant joining seven other variants under monitoring (VUMs) by WHO. It arose in February 2023 and appears to be dominating cases in the UK according to the CDC. Virus variants are mutations allowing the changed virus to transmit more readily between people and make it less sensitive to immune responses induced by either vaccination and/or previous virus infections.

The EG.5 variant is a lineage of (descended from) the Omicron variant of SARS-CoV2. So immunity to Omicron will provide a level of protection against EG.5 and lower the disease severity. It is important for people to stay up to date with their vaccine boosters as the threat of disease with these pandemic viruses is not over.

EG.5.1 is currently the fastest growing variant globally by proportion of total SARS-CoV-2 sequences. However, this is based on increasingly small numbers of sequences. It has been circulating since at least early 2023, but there has been increasing concern in recent weeks when it was noted to be growing in a number of countries in particular the UK, US and China. The variant is a descendent of the XBB sublineage and is still under the umbrella of Omicron variants. These XBB sublineages, such as XBB.1.5 have become the dominant variants across the globe over course of the last year.

EG.5.1 demonstrates a relative growth advantage over other circulating variants which is likely due to acquiring a small number of new mutations, a similar pattern throughout the evolution of Omicron variants since late 2022. It has not yet led to major changes in COVID-19 epidemiology in the settings where it has been identified.

However, both testing and sequencing data are considerably lower than earlier in the pandemic. Given these changes, there is the possibility of a small or moderate epidemic uptick in the coming weeks, such that persons with risk factors for severe outcomes from COVID-19 such as the elderly should consider familiar precautions to avoid exposure. These newer variants are descendants of the COVID-19 variants that make up current booster vaccines available in Australia.

However, newer vaccines containing more closely related XBB variants are currently in the pipeline which may provide improved protection in the coming months.

The pathogen genomics laboratory at NSW Health Pathology’s Institute of Clinical Pathology and Medical Research at Westmead has been identifying the EG 5.1 SARS-CoV-2 variant since late May. Over thirty have been detected, including from the community, from intensive care and from travellers to Australia. We do not know yet whether it is more transmissible, or causes more severe disease, and we continue to monitor SARS-CoV-2 variants in NSW.

Eris, the new Omicron subvariant taking off around the world, is somewhat misnamed. Eris is the Greek goddess of strife and discord, and the new subvariant is unlikely to live up to its name. The formal name for it is EG.5.1, or equivalently XBB.1.9.2.5.1, the latter showing that it is a recombination of previous subvariants. Because of its increased transmissibility, it has the potential to cause a fresh wave of cases in Australia, and countries like the UK and the USA are already seeing that happen.

Most Australians are “over” the pandemic, and don’t really care that another subvariant is on the increase. However, it is a timely reminder to elderly and other vulnerable people to wear an N95 face mask when out and about, and to get up to date with their booster shots. Sadly, less than 50% of elderly Australians are up to date with their COVID-19 boosters. The good news is that the new monovalent booster vaccine which will be arriving in Australia later this year, and based on XBB.1.5, should give good protection against this new subvariant.

The Omicron variant EG.5 was added to the World Health Organization Variants Under Monitoring in July 2023, and there has been a steady rise in infection globally related to this variant. Currently the variant EG.5.1, nicknamed Eris, is causing significant numbers of infection and is thought to have originated in Asia/the Western Pacific Region. It is unlikely that it is not already circulating in Australia. While locally, and globally, the number of infections related to COVID-19 continues to decline this is likely due to a significant decrease in testing, rather than being an indicator of decreased disease activity.

Eris seems to have more transmissibility than other variants and currently, for people experiencing illness with this variant, illness does appear to be mild. With COVID-19 no longer being regarded as a Public Health Emergency of International Concern we need to be mindful that this does not mean that the threat has gone away. Not everyone will experience a mild illness, and significant numbers of unwell people can cause disruption to individuals, families, and workplaces.

The community should be considering ways to reduce their risk, and the risk they pose to others if unwell. This includes managing their respiratory hygiene and wearing masks in settings with poor ventilation/crowds. Individuals should plan to be prepared, now and into the future, for illness by considering for how to access health care/testing and how they will isolate if unwell.

There are 68 known cases reported in Australia via whole genome sequencing with the first cases already detected in April/May. 

It represents a small iterative change compared to variants like XBB.1.5, with a key change in the Spike glycoprotein at position F456L.

The latter change we and others have observed to slightly lower the neutralisation titers of antibodies but at levels that are not significantly different to XBB.1.5.

Bivalent vaccine responses to EG.5.1 are similar to that observed for other XBB derived lineages like XBB.1.5. i.e. Antibody levels to this variant do increase following a booster dose.

The way the virus targets cells is similar to that observed for XBB.1.5, so there is no evidence that this variant will infect in a manner that is significantly divergent to XBB.1.5.

EG.5.1 is antigenically quite different to B.A.4/5, and the last boosters available in Australia were to the latter. These do not provide enough protection against EG.5.1, but the XBB subvariant boosters that are being made by most companies will protect against EG.5.1.  

In May this year, WHO recommended monovalent XBB boosters be made available. The US expects to have these boosters available in September. I have not yet heard an announcement about availability in Australia, but I hope it is being considered. 

COVID-19 is a serious infection that can cause longer term complications such as cardiovascular, neurological, immunological and respiratory complications in all age groups. Studies suggest getting re-infected may increase the risk of these. COVID-19 is the third leading cause of death in Australia (mostly due to the impact of Omicron), and is worth preventing.

We know that SARS-CoV2 is now endemic and new variants will keep emerging. New SARS-CoV2 variant EG.5.1 is spreading rapidly in the UK, the US, and some other countries, however the number of hospitalisations and deaths are the same at this stage. EG.5.1 may eventually replace existing circulating variants in Australia, however,  I think EG.5.1 will be less likely to cause a large epidemic in Australia due to the following reasons.

1) Currently there is no evidence to suggest that the new EG.5.1 variant causes more severe disease than previous variants.
2) Although breakthrough infections are very common now, we have quite high vaccination rates which is protecting against severe illness at least.
3) We are going into the summer soon. 

Increase in the number of cases of EG.5.1 in the UK and the US may be due more genomic sequencing, coupled with waning immunity, weather, more social mixing and traveling etc. However, we should be vigilant, and should increase surveillance and sequencing to detect and monitor the new strain. Vaccination should be continued, particularly in vulnerable groups.

WHO is still monitoring COVID-19 variants, though there are currently no SARS-CoV-2 variants meeting the variants of concern criteria. As of 19 July 2023, variants under monitoring by the WHO are BA.2.75, CH.1.1, XBB.1.9.1, XBB.1.9.2, XBB.2.3 and EG.5.1. Currently circulating variants of interest are XBB.1.5 and XBB.1.16. 

EG.5 (Eris) is a family of subvariants of Omicron that first appeared back in February. EG.5.1 is the particular variant within this family that has now just edged out the XBB and other Omicron descendants circulating in the United States and now makes up the largest proportion of COVID-19 cases nationwide across the US.
 
Eris has genetic similarities with the XBB lineage and so far infections do not appear to be associated with different symptoms or more severe illness. The challenge is that the genetic shift in a new subvariant can better evade our existing immune response to both vaccine as prior infection.
 
The variant was officially recognised by the World Health Organization as a Variant Under Monitoring on July 19 after a surge in COVID-19 infections from early July with increasing reports internationally, particularly in Asia.
 
India first saw this variant back in May, but there have only been sporadic cases since and no major rise in infections yet. Like Australia. In India the XBB sub-variant continues to be the dominant variant circulating in the country, accounting for 90-92% cases so far.
 
We have seen newly emerged Omicron variants take a few months to establish in Australia previously. With the waves in Australia are slowing and now spaced five months or more apart, the timing of EG.5.1 emergence might make this the subvariant that drives an increase here in late spring.

Despite the fact the public, the media and politicians have forgotten (or want to forget) about the COVID-19 pandemic that affected us all for over three years (and many still affected by Long COVID), the virus is still with us. SARS COV-2 has been steadily mutating in infected individuals and will continue to do so potentially producing more infectious and even virulent versions. There is not much evidence yet that the new Eris sub-variant is any more virulent than previous versions but its rapid surge implies that it is highly infectious.

This is becoming more clinically relevant because the population as a whole has not kept up with its vaccination boosters which may only work for a year or less in most people. Without that protection the virus is still dangerous and the new variants can almost certainly cause Long COVID (the incidence of which is reduced by vaccination). It is estimated that there are over 6 million people in the USA that have long COVID which creates a significant healthcare burden and is miserable for the individuals affected.

Australia has done quite well in avoiding the worst effects of acute and long COVID but a new variant exploding into a now rather unprotected population still has the potential to cause more suffering and morbidity. Let’s hope that we have all learned something from the previous COVID-19 experience so that a repetition of history can be avoided.

The situation with COVID-19 continues to evolve and essentially, as we have seen on countless previous occasions and therefore should come as no surprise, another new subvariant has arisen. This one is known as EG.5 or more specifically perhaps EG.5.1 and has also been given the name “Eris” which I believe is after the Greek god of strife and discord.

This variant was first identified in Indonesia and has spread globally. Its emergence, along with a host of additional contributing factors, is likely partly responsible for rises in cases recently in some parts of the world, although factors like waning immunity also are likely significant. As with the emergence of any new variant or subvariant, it is still early days so more information that takes some time to accumulate is required - but it has been suggested that the symptoms may be slightly different particularly in terms of a lower rate of fevers - although this too may be due to a combination of factors.

Other symptoms thought to occur commonly include runny nose, sneezing, headache and a sore throat. This subvariant has become dominant in many countries, for example it is now 17.3% of reported cases in the USA and its rate of detection has increased sharply in many other parts of the world. It seems the spike protein is still relatively closely related to subvariants already circulating including XBB.1.5 and the reason this is important as there are new boosters on the horizon targeting this subvariant so the expectation is these would still provide good protection against EG.5.

Personally I think the best way to look at the emergence of this new subvariant is that it was essentially inevitable and expected and should serve as a timely reminder that COVID-19 has not gone away and the basic measures we should all be familiar with including staying home when you are unwell, testing and taking antivirals if eligible and most importantly staying up to date with vaccination, particularly new updated boosters when they are available, remain important.

The recent news about a new COVID-19 variant is not surprising and indeed expected. Viruses evolve over time, and new variants are part of that process. It should also be noted that variants can become extinct which is likely to be the case for the Delta variant for example. The important point with all this is the need to be up to date with the latest COVID-19 vaccine. Older vaccines are not nearly as effective for the latest COVID-19 variants as are the latest bivalent vaccines. So if you are entitled to the next COVID-19 vaccine, please get vaccinated.

EG.5 is a subvariant of Omicron and likely arose from the Omicron XBB variant. Over the past few weeks, it has become the most frequently detected SARS-CoV2 variant in individuals reporting new infections in the US and UK.

EG.5 does seem to have greater transmissibility than other SARS-CoV2 variants however there is not enough evidence to suggest this is resulting in more cases of severe COVID-19 or in increased rates of hospitalisation. 

The current and updated COVID-19 vaccine boosters should provide reasonable protection against EG.5. This is because the spike proteins in this variant and previous variants – on which current vaccines are based – are very similar.