Amid a summer uptick in COVID-19 cases, a new COVID subvariant, EG.5, also referred to as Eris, has emerged and become the dominant strain in the United States. Many are wondering if this new COVID variant is causing different symptoms.
EG.5 now accounts for the largest proportion of COVID-19 infections in the country compared to any other variant, according to the U.S. Centers for Disease Control and Prevention.
On Wednesday, Aug. 9, the World Health Organization classified EG.5 as a variant of interest as cases increase globally.
The EG.5 variant quickly overtook the prevailing omicron XBB strains in the U.S. last month.
Over a two-week period ending on Aug. 5, EG.5 made up an estimated 17.3% of new confirmed COVID-19 cases in the U.S., up from 12% two weeks prior, according to the latest CDC estimates.
What is EG.5 , aka Eris?
EG.5 is a descendant of the omicron XBB sublineage of the virus (specifically, XBB.1.9.2). It has an extra mutation in its spike protein, according to a WHO risk evaluation report.
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"When we look at its sequence, EG.5 is really similar to the other XBB variants that are circulating right now, with a couple of small changes," Dr. Andrew Pekosz, a virologist at Johns Hopkins University, tells TODAY.com.
The WHO added EG. 5 to its list of variants under monitoring on July 19, 2023, but the variant was first detected in February 2023. "Scientists have known about this variant, and it’s been present in other countries, as well," says Pekosz.
So far, EG.5 has been detected in 51 countries and there has been a steady increase in prevalence globally — the majority of sequences are from China, followed by the U.S., South Korea, Japan and Canada, per WHO.
XBB.1.16, also called the “Arcturus” variant, remains the most prevalent strain of COVID-19 worldwide.
WHO considers the public health risk posed by EG.5 to be "low" and similar to that of XBB.1.16 and other variants of interest.
Is EG. 5 more transmissible?
The EG.5 variant is very similar to other omicron variants, which means it's highly transmissible, Dr. Albert Ko, an infectious disease physician and professor at Yale School of Public Health, tells TODAY.com.
However, EG.5 is likely more transmissible than other XBB variants, Dr. Sharon Nachman, chief of the division of pediatric infectious diseases at Stony Brook Children’s Hospital, tells TODAY.com.
"If it was equally transmissible, then we wouldn't see it gaining strength number-wise compared to some of the other variants," says Nachman, adding that EG.5 quickly pushed out other XBB variants in the U.S., which were dominant over the summer.
Why exactly EG.5 is more transmissible is not yet known, Ko says.
“Whether it's escaping population immunity or it has some intrinsic factor that makes it better able to transmit from one person to another ... it’s hard to separate,” he adds.
According to WHO, EG.5 has increased immune escape properties compared to other variants. "EG.5 may cause a rise in case incidence and become dominant in some countries or even globally," WHO said in a report.
However, Pekosz notes that the EG.5 variant may not be the sole reason for the U.S. summer uptick. “When you have a new variants, and cases creeping up, there’s always concern about whether that variant could be driving the increase,” says Pekosz.
“Right now, it doesn’t look like that variant alone is driving the case increases (in the U.S.) ... there’s still a lot of other variants co-circulating," he adds.
According to CDC estimates, EG.5 accounted for about 17% of COVID-19 cases in the U.S. during the two-week period ending on Aug. 3. — after EG.5, the next most common variants were XBB.1.16, XBB.2.3, and XBB.1.5, which accounted for 15%, 11% and 10% of cases, respectively.
"We're keeping an eye on (EG.5) because of the uptick in cases, but it doesn't look like there's anything particularly concerning about this variant," says Pekosz.
More data is needed to understand how EG.5's transmissibility compares to other strains. However, decreased levels of testing and genomic sequencing are making it harder to accurately track new COVID-19 cases and which variants are driving them, Pekosz notes.
"Right now, there's an awful lot of guesswork," he says.
Is EG.5 more severe?
The data available do not indicate that EG.5 causes a more severe infection compared to other variants, the experts note.
In its risk assessment of EG.5, WHO said, "There have been no reported changes in disease severity to date."
Although the U.S. recently saw the first increase in COVID-19 hospitalizations of the year, there isn't evidence that EG.5 is causing this uptick or that it's more likely to cause hospitalizations in general, Nachman notes.
"The people that are getting hospitalized often have lots of co-morbidities, and they're at-risk no matter what COVID strain they get," says Nachman.
However, it’s possible that hospitalizations could increase even more because of more people getting infected with EG.5, says Ko. “There’s no clear evidence of that at this point, but we have to keep on evaluating,” Ko adds
Population immunity from vaccination and prior infection should protect people from severe illness as EG.5 continues to circulate.
What are the symptoms?
There isn't enough clinical data about the most common symptoms of EG.5 yet, NBC News previously reported.
"There's no change in EG.5 symptoms right now," says Pekosz. So far, the symptoms of EG.5 look very similar to the standard omicron symptoms, says Ko. These include:
- Cough
- Sore throat
- Runny nose
- Sneezing
- Fatigue
- Headache
- Muscle aches
- Altered sense of smell
"It may progress to some more significant feelings of difficulty in breathing as the infection spreads into your lungs," says Pekosz.
Certain groups are at higher risk of developing severe illness or complications, including people over 65 and those who are immunocompromised or have underlying medical conditions.
Can COVID-19 tests detect EG.5?
All COVID-19 tests — including PCR tests performed by a medical provider and rapid at-home antigen tests sold over-the-counter — should be detecting EG.5, says Pekosz.
The experts emphasize the importance of getting tested as COVID-19 cases increase, and especially during the fall when viruses that cause similar symptoms (such as flu and RSV) are circulating.
"If you’re in one of the high-risk groups for getting severe COVID, you really shouldn't hesitate to get a test," says Pekosz, adding that early detection and treatment is key. COVID-19 antivirals such as Paxlovid are effective against EG.5 and other variants, but they work best when taken early, he adds.
Whether your insurance covers COVID-19 testing may have changed since the end of the U.S. federal public health emergency in May, TODAY.com previously reported, so check with your insurer if you have questions about testing costs.
It’s also important to check the expiration date of at-home tests. The shelf life of rapid tests ranges from four to 24 months, according to the U.S. Food and Drug Administration, but the expiration dates of some tests have been extended.
Will I need a COVID-19 booster this fall?
The experts encourage everyone to stay up to date on COVID-19 vaccines, which may include a new booster dose in the coming months. In June 2023, the FDA advised vaccine manufacturers to update their boosters to target omicron XBB.1.5, which was the dominant strain at the time.
These shots haven't been approved yet, but the FDA could authorize Pfizer's booster shot by the end of August, NBC News reported.
Although the new boosters will not include the EG.5 strain, they may still provide protection, the experts note. “If I vaccinate you with the vaccine that contains XBB, you will make antibodies that are specific to XBB and pretty close to EG.5,” says Nachman.
"Right now, EG.5 looks like it's very closely matched to the vaccine that's going to be available this fall," says Pekosz.
However, the CDC has not yet released any firm guidance or recommendations around booster doses for the fall.
"The message is to pay attention to the COVID vaccine program that's going to come out in the fall. ... It's a vaccine that many people (especially high-risk individuals) should consider taking," says Pekosz.
How to protect yourself from EG.5:
In addition to staying up to date on COVID-19 vaccinations, the experts emphasize taking precautions to protect yourself and curb transmission of COVID-19, including:
- Washing your hands with soap and water frequently
- Staying home when sick
- Avoiding contact with sick people
- Improving ventilation
- Wearing a mask in crowded, indoor spaces
- Covering coughs and sneezes
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