New COVID "Eris" Variant Now Dominant as U.S. Cases Tick up

Jennifer Middleton, MD, MPH
Posted on August 28, 2023

The latest COVID variant of concern, EG.5 (nicknamed “Eris”), is now the dominant strain in the United States, the United Kingdom, and China; in the United States, it accounts for 17% of current COVID cases according to the Centers for Disease Control and Prevention (CDC). Although this latest SARS-CoV-2 variant does not seem to cause more severe disease than the XBB variants, some scientists are concerned that EG.5’s spike protein mutations may “may make it slightly less susceptible to antibodies in previously vaccinated and/or infected people.”

EG.5 was first identified by the World Health Organization (WHO) in February 2023 and is a “is a subvariant and descendant of omicron, which is still the world’s most prevalent strain.” EG.5’s most common symptoms, rhinorrhea, dry cough, and sneezing, aren’t that different from prior COVID variants and strains; unfortunately, as flu season approaches in the United States, these symptoms aren’t that different from influenza either. COVID infection rates have been increasing over the last few weeks in the United States, although they are “still more than 90% below peak levels hit during the January 2022 Omicron outbreak.” Prescriptions for nirmatrelvir/ritonavir (Paxlovid) have increased a bit in the United States, though, and the amount of SARS-CoV-2 detected in U.S. wastewater is also up.

Researchers are testing serum samples from people who received the updated vaccine in trials for effectiveness against EG.5.  Despite concerns about EG.5’s ability to evade antibodies, most scientists still believe that the anticipated fall COVID booster in the United States will still provide reasonable protection against EG.5:

The updated booster was developed based on another variant that is genetically similar to EG.5. It is expected to provide better protection against EG.5 than last year’s shot, which targeted the original coronavirus strain and a much earlier Omicron variant that is only distantly related.

Although 70% of the U.S. population is fully vaccinated* against COVID, these rates are much lower in children: only 2% of children 6 to 24 months of age, 4% of children 2 to 4 years of age, and 32% of children 5 to 11 years of age. With the school year starting in most parts of the United States, the rate of COVID cases could accelerate again, and we should be encouraging COVID vaccination at all well checks, daycare physicals, and school physicals.

The AFP By Topic web page on COVID-19, which can be found on American Family Physician's website, continues to be updated; the page contains resources on risk stratification, point-of-care testing, and long COVID, among others. You can follow the rate of vaccine uptake here, and the CDC and WHO also have websites dedicated to COVID-19 updates.

*—"Fully vaccinated” includes only the initial vaccination series and does not include the percentage of people who have received booster doses; booster rates vary widely by state.