EG.5 Is Now the Dominant COVID-19 Variant in the U.S.

After months of relatively low levels of COVID-19, cases are rising across the country. Meanwhile, health officials are keeping their eye on a new variant that’s steadily gaining ground in the United States.

EG.5, nicknamed “Eris,” is a descendant of Omicron. The variant is now estimated to make up 17.3% of U.S. cases, making it the dominant variant. At the end of May, the variant accounted for only 1% of all domestic COVID cases, according to the data tracker by the Centers for Disease Control and Prevention (CDC).

On July 19, the World Health Organization named EG.5 and its descendants “variants under monitoring.” That means the variant may have genetic changes that could make it more transmissible than other variants, though more research and monitoring is necessary to know for sure.

EG.5 is closely related to some of the widely circulating “XBB” variants. Cases of EG.5 also make up a large portion of cases in countries including China, Britain, and Japan.

Will EG.5 Cause Another COVID Surge?

COVID hospitalizations were up 12.5% in the week ending July 28, according to the CDC. It’s challenging to track how widely the virus is circulating this summer, as most people are now testing with at-home kits rather than PCR or don’t test at all.

However, wastewater surveillance indicates cases are on the rise, too. Nearly half of all reporting sites saw an uptick in cases as of July 20.

EG.5 and its child EG.5.1 still account for less than 20% of infections in the U.S., so the increase in hospitalizations is perhaps not entirely variant-driven, said T. Ryan Gregory, PhD, an evolutionary biologist at the University of Guelph in Ontario.

Immunity from vaccination and infection wanes over time, leaving people more vulnerable to infection and severe disease. Factors like the dropping of masking protection and more indoor gatherings could also contribute to the current summer wave, Gregory said.

At this stage of the pandemic, it’s not as likely that a new variant will cause a tsunami of cases. Gregory said it’s more likely scientists will see a “rising sea level”—a higher baseline of cases that won’t get lower.

“A sustained high baseline means a lot of infections overall, which means more long COVID and more variant evolution,” Gregory told Verywell in an email.

Will Vaccines Still Work Against EG.5?

The last time the vaccines were updated, they were made to target both the original COVID-19 strain as well as Omicron BA.4 and BA.5.

In June, federal regulators asked Pfizer, Moderna, and Novavax to create a new formulation of their COVID-19 vaccines.

The upcoming boosters will target XBB.1.5, nicknamed “Kraken.” Eris is an XBB descendent too and is only two mutations away from XBB.1.5, which means the new boosters will likely be effective against severe illness from EG.5.

Gregory said he doesn’t expect that the mutations Eris carries would cause more severe or different symptoms than other circulating variants.  

“It’s very difficult to assess the severity or symptoms for any particular variant these days, when several are circulating at the same time and when there is so little testing,” Gregory said.

CDC Director Mandy Cohen told NPR this week that the boosters would be ready in “early October.”

How Can You Protect Yourself From COVID?

The risks of hospitalization and death from COVID are much lower now than in years past, due to vaccination and infection-induced immunity.

Still, COVID is not a cold or the flu, and with infection comes the risk of debilitating long COVID.

While vaccines can protect against severe disease, they don’t always prevent transmission or long COVID. As has been true throughout the pandemic, the best safety protocol is to wear a well-fitting face mask, avoid unnecessary exposure risk, practice good hand-washing, and test for COVID-19 after exposure or when experiencing symptoms.

If you're using an at-home rapid test, Gregory recommends swabbing your throat, the inside of your cheeks, and your nose to reduce the chance of false positives. If you get a negative result, take another test a day or two later to confirm.