As the seasons shift and we head into the time when respiratory viruses typically become more active, the SARS-CoV-2 virus continues its journey of change and adaptation. This ongoing evolution means we see new versions of the virus emerge, and keeping informed about them is a key part of navigating the current situation.
One particular variant has been making headlines recently, capturing attention around the globe. Nicknamed “Eris,” this variant, officially known as EG.5, has quickly become a prominent player in the circulation of the virus.
So, what exactly is Eris, and what do we need to know about it as we move forward? Let’s dive into the details based on the latest information from health experts and organizations monitoring its spread.
EG.5 is a descendant of the well-known Omicron variant, specifically stemming from the XBB sublineage. It’s described as an offshoot of Omicron and a descendant of XBB.1.9.2, featuring an extra mutation in its spike protein. Dr. Andrew Pekosz, a virologist at Johns Hopkins University, notes that when looking at its sequence, EG.5 is “really similar to the other XBB variants that are circulating right now, with a couple of small changes.”
This variant was first detected back in February 2023, but gained official recognition from the World Health Organization (WHO) more recently. The WHO added EG.5 to its list of variants under monitoring on July 19, 2023, before classifying it as a “variant of interest” on August 9.
Its informal name, “Eris,” was coined on social media by health experts and has stuck. This catchy moniker makes it easier to discuss, and its prevalence makes it a significant point of focus right now.
EG.5 has spread remarkably fast. It has been reported in a total of 73 countries, and its prevalence continues to rise globally. The majority of sequences are coming from countries like the U.S., China, Japan, and South Korea.
In the United States, Eris has surged to become the dominant strain, according to data from the U.S. Centers for Disease Control and Prevention (CDC). The latest figures show that EG.5 accounted for an estimated 23.6% of new COVID cases during a two-week period ending on October 14.
This makes it the largest proportion of infections by far, more than any other single variant in the country. Following EG.5 in prevalence are other Omicron descendants like HV.1, FL.1.5.1 (dubbed “Fornax”), and XBB.1.16 (known as the “Arcturus” subvariant), showing the diverse mix of strains still circulating.
Its rapid rise leads many to wonder if EG.5 is more transmissible than its predecessors. While it is highly transmissible like earlier Omicron variants, according to Dr. Albert Ko, an infectious disease physician and professor at Yale School of Public Health, experts like Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children’s Hospital, believe EG.5 is likely more transmissible than other XBB variants.
Dr. Nachman explains, “If it was equally transmissible, then we wouldn’t see it gaining strength number-wise compared to some of the other variants.” Its ability to quickly push out other formerly dominant XBB variants in the U.S. supports this idea.
The precise reasons behind EG.5’s potential increased transmissibility aren’t fully understood yet. Dr. Ko points out the difficulty in separating whether it’s due to “escaping population immunity or [whether] it has some intrinsic factor that makes it better able to transmit from one person to another.”
WHO’s reports indicate that EG.5 does have increased immune escape properties compared to some other variants. They stated that “EG.5 may cause a rise in case incidence and become dominant in some countries or even globally,” which we are now seeing happen.
However, it’s important to note that while EG.5 is dominant, it might not be the only factor driving recent increases in cases observed in places like the U.S. over the late summer and early fall. Dr. Pekosz notes, “It doesn’t look like that variant alone is driving the case increases… There’s still a lot of other variants co – circulating.”
The summer uptick in the U.S., for instance, was likely fueled by a combination of EG.5 and other circulating Omicron variants. Factors like reduced masking, increased travel, extreme heat driving people indoors, and waning immunity from previous infections and vaccinations also play significant roles.
A key question on everyone’s mind is whether Eris causes more severe illness. The good news here is that the available data do not suggest EG.5 leads to more severe infections compared to other variants we’ve encountered. The WHO’s risk assessment notes, “There have been no reported changes in disease severity to date.”
While the U.S. did see an increase in COVID – 19 hospitalizations earlier this year, there’s no clear evidence linking this directly to EG.5 causing more severe outcomes in general. Dr. Nachman highlights that people being hospitalized often have co – morbidities and are at risk regardless of the specific strain.
Dr. Ko suggests it’s possible hospitalizations could increase simply because more people are getting infected, but emphasizes, “There’s no clear evidence of that at this point, but we have to keep on evaluating.” Population immunity built up through vaccination and prior infection continues to provide good protection against severe outcomes even as EG.5 spreads.
When it comes to symptoms, the picture appears consistent with what we’ve seen from previous Omicron strains. While comprehensive clinical data specifically on EG.5 symptoms is still being developed, experts report no significant changes so far.
Dr. Pekosz says, “There’s no change in EG.5 symptoms right now.” Dr. Ko adds that the symptoms look very similar to standard Omicron symptoms. These commonly include a runny nose, headache, fatigue (ranging from mild to severe), sneezing, and a sore throat.
Other reported symptoms linked to Omicron and potentially seen with Eris include cough, muscle aches, and an altered sense of smell. While less common, diarrhea, eye irritation, and rashes have also been reported with some Omicron variants.
In some cases, the infection might progress, leading to more significant symptoms like difficulty in breathing if it spreads to the lungs, according to Dr. Pekosz. As with any variant, certain groups remain at higher risk for severe illness or complications, including those over 65, immunocompromised individuals, and people with underlying medical conditions.
Effective testing remains a crucial tool, especially during the fall and winter when other respiratory viruses like flu and RSV are circulating and can cause similar symptoms. The good news is that existing COVID – 19 tests should be able to detect EG.5.
Both PCR tests, typically performed by a medical provider, and rapid at-home antigen tests, available over-the-counter, are expected to detect the presence of the Eris variant. Dr. Pekosz confirms that all these tests “should be detecting EG.5.”
Experts stress the importance of getting tested if you have symptoms, particularly if you are in a high-risk group, because early detection can lead to early treatment. COVID-19 antivirals like Paxlovid have been shown to be effective against EG.5 and other variants.
Antiviral treatments like Paxlovid work best when taken early in the course of the illness. It’s a treatment that involves taking pills orally twice a day for five days and is available by prescription. It can help reduce the risk of severe illness, hospitalization, and potentially long COVID.
Finding testing has changed since the end of the U.S. federal public health emergency in May. Insurance coverage for testing may have changed, so it’s wise to check with your insurer about costs. Also, if you’re using at-home tests, remember to check the expiration date; while shelf lives typically range from four to 24 months, the FDA has extended the expiration dates for some test brands based on manufacturer data.
A significant layer of protection comes from vaccination. A new COVID-19 vaccine is available this fall, and the CDC recommends it for everyone aged 6 months and older. Millions of doses have been distributed, making them accessible at pharmacies and doctor’s offices.
These updated vaccines from manufacturers like Moderna, Pfizer (mRNA), and Novavax (protein-based) were reformulated to target the Omicron XBB.1.5 strain, which was dominant for much of 2023. While Eris, Fornax, and Arcturus have since become more prevalent, they are close relatives of XBB.1.5.
This close relationship is key to why the new boosters are expected to provide good protection against Eris and other recently circulating strains. Dr. Nachman explains that vaccinating with the XBB-containing vaccine prompts your body to produce antibodies “specific to XBB and pretty close to EG.5.
Dr. Pekosz concurs, stating, “Right now, EG.5 looks like it’s closely matched to the vaccine that’s going to be available this fall.” He adds that it is a vaccine that many people, especially those in high-risk groups, “should consider taking.” The updated vaccine should also help protect against the new BA.2.86 or “Pirola” strain.
Speaking of Pirola (BA.2.86), it’s another variant making waves, detected in several countries including the UK, Israel, Denmark, and the US. Pirola is also a sub-variant of Omicron but stands out due to its numerous mutations – 34 more mutations than the BA.2 variant, according to virologist Professor Lawrence Young.
These significant genetic differences have led experts to be concerned about Pirola’s potential to evade immunity. Professor Azeem Majeed notes concerns that new variants might “evade immunity and cause more serious disease than previous variants.” Professor Christina Pagel echoed this, saying Pirola has “a lot of new mutations that make it very different from previous Omicron strains.”
However, current assessments, like those from the CDC regarding cases detected in the US as of late August, suggest Pirola is not likely driving current hospitalizations yet, though this assessment could change. Experts also emphasize that prior immunity from vaccination and infection “continues to provide good protection for most people” against severe disease from these new variants.
Beyond vaccination and staying updated on boosters, there are several practical steps recommended by experts to protect yourself and help curb transmission of COVID-19 variants like Eris and Pirola. These are familiar measures, but their effectiveness remains high.
Practicing good hygiene, such as washing your hands frequently and thoroughly, is fundamental. If you’re feeling unwell or test positive, staying home and away from others is essential to prevent spread, especially to vulnerable individuals.
Improving ventilation indoors is also a valuable tactic. Simply letting fresh air into your home or using appropriate filters in your HVAC system with continuous airflow can make a difference in reducing viral particle concentration. Maintaining distance in crowded indoor areas and avoiding contact with people who are clearly sick are also helpful.
For those at higher risk of serious illness, including older people, immunocompromised individuals, and those not recently vaccinated, wearing a well-fitted mask or respirator in public or crowded indoor spaces offers an extra layer of protection against respiratory droplets.
With multiple respiratory viruses circulating this season, knowing when to get tested if you have symptoms is important. Experts advise testing as early as two days after potential exposure if symptoms appear.
A crucial update for this stage of the pandemic, particularly in 2024, is not to fully trust a negative early COVID-19 test. Due to accumulated immunity from vaccinations and prior infections, your immune system might react faster, causing symptoms before you have a high enough viral load for an at-home antigen test to register positive.
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As Dr. Chin-Hong notes, your immune system gets “agitated and active, and you begin to get sick sooner, but you actually don’t have as much virus in your blood yet.” This mismatch means that if your first test is negative but symptoms persist, you should test again 48 hours later. PCR tests, being more sensitive, can also be sought out.
The recent rise in cases, attributed to variants like Eris and other factors, serves as a reminder to stay vigilant as we head into cooler months. As Dr. Rebekah Sensenig notes, when it’s cold, we spend more time inside where viruses spread faster.
The World Health Organization expects us to be dealing with COVID-19 for years to come, but we have the tools to reduce risk and prevent severe illness. These tools include the updated vaccines, testing, and consistent protective behaviors.
Finding free or low-cost testing has become more challenging, but options still exist. The federal government has restarted its service for ordering free at-home tests. Tests can also be purchased at pharmacies (potentially reimbursable by insurance), found at some local public libraries, or accessed through healthcare providers and specific testing sites, including some free PCR sites listed by entities like the CDC or state health departments.
Ultimately, navigating the continued presence of COVID-19 and its evolving variants like Eris and Pirola is about being informed and proactive. Understanding the landscape, utilizing the available vaccines and treatments, and consistently applying protective measures empower us to stay healthier and protect our communities through this respiratory virus season and beyond.
It’s not about alarm, but about awareness. The virus continues to change, but so do our defenses and our knowledge. By staying informed and prepared, we can face the season ahead with greater confidence, ensuring we do our part to mitigate spread and protect those most vulnerable among us. Our ability to adapt and utilize the science available is a powerful response to the ongoing evolution of this virus.
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