What are the symptoms of EG.5 or Eris, the dominant COVID variant in the US?

As the United States enters its respiratory virus season and rolls out an updated COVID booster, the SARS-CoV-2 virus continues to circulate and mutate. This summer, a new variant called EG.5 swept across the U.S. and quickly overtook the prevailing omicron strains circulating in the country.

EG.5 is an offshoot of omicron and a descendant of the XBB sublineage. The fast-spreading subvariant, nicknamed "Eris," is now the dominant COVID-19 strain worldwide.

In the U.S., EG.5 accounts for the largest proportion of COVID-19 infections, more than any other variant, according to the latest data from the U.S. Centers for Disease Control and Prevention.

According to the CDC, EG.5 made up an estimated 23.6% of new COVID cases during a two-week period ending on Oct. 14. After EG.5, the next most common strain is another descendant of omicron XBB, HV.1, followed by FL.1.5.1 or "Fornax," and XBB.1.16 or the “Arcturus” subvariant.

Since the late summer, the U.S. has seen a surge in COVID-19 cases and hospitalizations., likely driven by a combination of EG.5 and other omicron variants circulating, TODAY.com previously reported.

Fortunately, hospitalizations have started to trend downward. In the last two weeks, there was a 9.5% decrease in the number of average daily COVID-19 hospitalizations, according to an NBC News analysis.

However, EG.5 is still spreading and infecting people around the country. Many are wondering if the subvariant is more transmissible or severe, whether it could cause different symptoms, and if the new COVID-19 vaccines will provide protection.

Here’s what we know about Eris so far, according to experts.

What is EG.5 , aka Eris?

EG.5 is a descendant of XBB.1.9.2, with an extra mutation in its spike protein, according to a WHO risk evaluation report.

"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.

EG.5 was dubbed “Eris” on social media by health experts, which has become its unofficial name.

On Aug. 9, the World Health Organization decided to classify EG.5 as a “variant of interest.”

So far, EG.5 has been reported in 73 countries total and continues to increase in prevalence globally — the majority of sequences are from the U.S., China, Japan, and South Korea, per the WHO.

WHO considers the overall 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 earlier omicron variants, which means it's also 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 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.

“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 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 vaccine this fall?

There is a new COVID-19 vaccine available, which the CDC is recommending for everyone ages 6 months and older this fall, TODAY.com previously reported. Since federal health officials approved the updated vaccine in September, millions of doses have arrived at pharmacies and doctor's offices around the country.

So far, the FDA has authorized three vaccine options for 2023-2024 — two mRNA vaccines from Moderna and Pfizer, for everyone ages six months and older, and a protein-based non-mRNA shot from Novavax, for everyone ages 12 and older.

The new vaccines were reformulated by manufacturers to target omicron XBB.1.5, which was the dominant strain circulating for most of 2023. It has since been overtaken by Eris, Fornax, and Arcturus, but these are close relatives of XBB.1.5.

So although the new boosters do not include the EG.5 strain, they are expected to provide good protection against it and other recent strains circulating. The updated vaccine should also protect against the new BA.2.86 or "Pirola" strain, according to experts.

“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 closely matched to the vaccine that's going to be available this fall," says Pekosz. "It's a vaccine that many people (especially high-risk individuals) should consider taking," Pekosz adds.

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:

• Stay up to date with COVID-19 vaccines

• 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

This article was originally published on TODAY.com