August 10, 2023: The WHO has updated the EG.5 variability of the COVID-19 virus to a ‘variant of interest’ — with genetic changes that are predicted or known to affect virus characteristics, such as transmissibility, virulence, antibody evasion, susceptibility to therapeutics and detectability.
The update of the SARS-CoV-2 variant showed it has a growth advantage over other circulating variants in more than one WHO region with increasing relative prevalence alongside an increasing number of cases over time.
The new classification also brought in other apparent epidemiological impacts to suggest an emerging risk to global public health.
The public health risk posed by EG.5 was evaluated as “low at the global level,” and the WHO stated that due to its growth advantage and immune escape characteristics, EG.5 may cause a rise in case incidence and become dominant in some countries or even globally.
The variant EG.5 was earlier categorized by the global health agency as a ‘variant under monitoring,’ which means genetic characteristics and early signals of growth advantage relative to other circulating variants were confined to only one WHO region or globally.
Epidemiological impact unclear
According to the earlier classification, evidence of phenotypic or epidemiological impact remained unclear, requiring enhanced monitoring and reassessment pending new evidence.
EG.5 is a descendent lineage of XBB.1.9.2, which has the same spike amino acid profile as XBB.1.5. EG.5 was first reported on 17 February 2023 and designated as a variant under monitoring (VUM) on 19 July 2023.
With a new risk evaluation, The WHO designated EG.5 and its sub-lineages as a variant of interest, according to a WHO statement.
EG.5 carries an additional F456L amino acid mutation in the spike protein compared to the parent XBB.1.9.2 subvariant and XBB.1.5.
Additional spike mutation
Within the EG.5 lineage, the subvariant EG.5.1 has an additional spike mutation Q52H and represents 88% of the available sequences for EG.5 and its descendent lineages.
As of 7 August 2023, 7354 sequences of Omicron EG.5 have been submitted to GISAID from 51 countries.
The largest portion of EG.5 sequences are from China (30.6%). The other countries with at least 100 sequences are the US (18.4%), the Republic of Korea (14.1%), Japan (11.1%), Canada (5.3%), Australia (2.1%), Singapore (2.1%), the UK (2.0%), France (1.6%), Portugal (1.6%), and Spain (1.5%).
Globally, there has been a steady increase in the proportion of EG.5 reported. During July, 17-23, 2023, the global prevalence of EG.5 was 17.4%.
“This is a notable rise from the data reported four weeks prior, when the global prevalence of EG.5 was 7.6%,” according to the WHO. The Covid-19 virus has claimed the lives of 6.9 million people globally so far.