The EG.5 variant of SARS-CoV-2, identified in February 2023, has been classed as a “variant of interest (VOI) by the WHO. A sub-variant of the Omicron variant, it is nicknamed “Eris” after the Greek goddess of “strife”. However, despite its apparently greater ability to infect and evade immunity, there is “no sign” of more severe disease. So, as cases rise across the world, what interventions are available or on the way?
Eris, goddess of strife
EG.5 contains some of the same mutations as XBB.1.5, which is also known as the “Kraken” variant. However, EG.5 has an extra an F456L amino acid mutation in the spike protein, with early research indicating that this is helping EG.5 to evade neutralisation by antibodies in body fluids. A further spike protein mutation is called Q52H, the “implications of which are unknown”.
The variant was reported in February 2023 before designation as a “variant under monitoring” in July 2023. This means that genetic changes are “suspected to affect virus characteristics” and “early signals of growth advantage relative to other circulating variants” but the effects remain “unclear”. In August 2023 it has been detected in 51 countries, with Gavi suggesting that “regional differences in surveillance” may mean it is in circulation undetected elsewhere.
In August 2023 the WHO upgraded EG.5 to a VOI, which means that it has genetic changes that “affect virus characteristics such as transmissibility, virulence, antibody evasion, susceptibility to therapeutics, and detectability”. Furthermore, it is “identified to have a growth advantage” over other variants in “more than one WHO region”. Despite this, the global public health risk is deemed “low” due to the lack of reported changes in disease severity.
Antibodies and interventions
Gavi heard from Professor Eric Topol of the Scripps Translational Science Institute in La Jolla that Eg.5 is “likely” to have emerged through widespread use of monoclonal antibodies as treatment for COVID-19 infections. Recognising that they are effective, Gavi indicates that they can “inadvertently drive the development of viruses”.
As the variant partially evades antibody neutralisation, COVID-19 vaccines are less likely to be as effective than against earlier variants. Furthermore, it is understood that in the months after vaccination, antibody levels decline. Despite this, a person who has received several vaccines and/or booster vaccines is better prepared to mount a faster and stronger immune response.
What vaccines do we have?
CDC’s Dr Mandy Cohen told NPR that a new booster is expected in the “early October time frame”. She emphasised that the vaccine manufacturers and FDA experts are “undergoing that process” now.
“We can use the vaccines, the testing, and the treatment that we have to protect folks.”
Although these vaccines are expected to be ready in the US later this year, Professor Topol tweeted that they are delayed due to the end of the Public Health Emergency declaration in May 2023. This means that vaccines require a Product Licensing Application (PLA) instead of an EUA. Professor Topol also commented on the inflated cost of these vaccines.
“It is despicable that the COVID vaccine manufacturers are going to charge more than $110/dose.”
He refers to previous government support and the medical need, factors that were highlighted in Secretary Becerra’s letter to manufacturers recently.
