EG.5 emerges as dominant variant amid summer wave of COVID-19
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Key takeaways:
- EG.5, an omicron subvariant, has emerged as the predominant SARS-CoV-2 virus in the United States.
- WHO has classified EG.5 as a “variant of interest” but considers the global public health risk to be low.
The EG.5 omicron subvariant has emerged as the predominant SARS-CoV-2 virus during a summer wave of COVID-19 in the Unted States, accounting for 17.3% of cases, according to CDC tracking.
WHO has designated EG.5 as a “variant of interest” because of its quick spread but classified the public health risk posed by the virus as “low at the global level.” In interviews, experts expressed similar opinions.
“When we look at the virus sequence and what happened in other countries that had EG.5 infections, it appears unlikely that this variant will cause a massive surge in cases similar to what we saw when omicron or delta first emerged in humans,” Andrew S. Pekosz, PhD, professor and vice chair of the department of molecular microbiology and immunology at the Johns Hopkins University Bloomberg School of Public Health, told Healio.
In a risk assessment published Aug. 9, WHO said the variant “has shown increased prevalence, growth advantage, and immune escape properties” but “there have been no reported changes in disease severity to date.”
As the variant has emerged, new COVID-19 hospital admissions in the U.S. have increased 12.5% in the most recent week and deaths have increased 10%, according to the CDC. (The agency stopped aggregating COVID-19 cases and deaths in May and now uses hospital admissions and the proportion of COVID-19 deaths among all U.S. deaths as its primary surveillance metrics.)
“Overall, EG.5 looks like a closely related sibling to XBB.1.5 that is a bit more immune evasive but not revolutionarily so,” Jonathan Z. Li, MD, an associate professor of medicine at Harvard Medical School and director of the Harvard/Brigham Virology Specialty Laboratory, told Healio.
“I would expect prior infection with omicron to be protective and minimal change in current vaccine efficacy against EG.5 compared with XBB. There also does not appear to be any impact on currently available antiviral therapies,” Li said.
XBB.1.5 became the dominant omicron subvariant in January after evolving to be significantly more transmissible than previous variants, and was significantly more immune-evasive that variants before it, experts said at the time.
Pekosz said EG.5 contains a new mutation to the SARS-CoV-2 spike protein that may lead to some escape from antibodies induced by previous infection or vaccination but agreed it is very similar in most ways to XBB subvariants and observed that the summer wave of cases has fallen short of a surge.
“EG.5 cases are increasing, but overall case numbers are still low,” Pekosz told Healio.
At a media briefing, WHO Director-General Tedros Adhanom Ghebreyesus, PhD, MSc, noted that COVID-19 cases, hospitalizations and deaths have declined significantly since he ended the global public health emergency for the coronavirus in May but also said many countries have stopped reporting data.
“In the past month, only 25% of countries and territories have reported COVID-19 deaths to WHO, and only 11% have reported hospitalizations and ICU admissions,” Tedros said. “This doesn’t mean that other countries don’t have deaths or hospitalizations, it means they are not reporting them to WHO.”
Paul Biddinger, MD, FACEP, chief of emergency preparedness at Massachusetts General Hospital, said Mass General Brigham’s 14 hospitals have seen a “slow rise” in cases since early July, when they were “close to our lowest values across our health care system since the pandemic began.”
Biddinger said there are roughly 50 patients in the hospital system who have tested positive for COVID-19, 10 of whom are hospitalized specifically for COVID-19, including two in the ICU.
“These numbers are about twice as high as our recent nadir, but we are well below where we were in the early spring,” Biddinger said.
Pekosz said the emergence of EG.5 should not affect the manufacturing of this fall’s updated monovalent COVID-19 vaccines, which are based on the XBB spike protein. EG.5 is very similar, he said.
“EG.5 and the XBB family of variants have sequences that are very different from the ones used in the previous bivalent COVID vaccine. That, combined with the fact that it has been some time since most people received a COVID booster vaccine, would indicate that EG.5 could cause infections in previously vaccinated people,” Pekosz said. “One more reason to consider getting the fall COVID vaccine, as that will be much more protective.”
References:
- CDC. COVID Data Tracker: United States COVID-19 hospitalizations, deaths, emergency department (ED) visits, and test positivity by geographic area. https://covid.cdc.gov/covid-data-tracker/#maps_new-admissions-rate-county. Published Aug. 10, 2023. Accessed Aug. 11, 2023.
- CDC. COVID Data Tracker: Variant proportions. https://covid.cdc.gov/covid-data-tracker/#variant-proportions. Accessed Aug. 11, 2023.
- WHO. EG.5 Initial risk evaluation, 9 August 2023. https://www.who.int/docs/default-source/coronaviruse/09082023eg.5_ire_final.pdf. Published Aug. 9, 2023. Accessed Aug. 11, 2023.
- WHO. WHO director-general’s opening remarks at the media briefing, 9 August 2023. https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing---9-august-2023. Published Aug. 9, 2023. Accessed Aug. 11, 2023.
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