By Tristan Manalac

Pictured: Healthcare worker administering a vaccine into a patient's arm/iStock, Tirachard
Moderna on Thursday announced that its updated COVID-19 vaccines can induce neutralizing antibodies against the emerging EG.5 and FL.1.5.1 variants of the virus, dubbed Eris and Fornax, respectively.
Pfizer, along with German partner BioNTech, also said on Thursday that its updated shots elicited strong neutralizing activity against the Eris subvariant in a mouse study, reported Reuters.
These updated vaccines come just in time for the fall vaccination season, for which the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) in June unanimously recommended using a monovalent vaccine focusing on the Omicron XBB.1.5 subvariant.
According to data from the CDC, XBB.1.5 was the most dominant Omicron subvariant in the U.S. throughout most of 2023, accounting for 73.5% of cases in the latter half of April and 64.5% in the first half of May.
In the last two weeks, however, the Eris subvariant has started to slowly overtake XBB.1.5 and as of Aug. 5 is responsible for approximately 17.3% of cases. Meanwhile, the Fornax subvariant caused around 8.6% of coronavirus infections as of this date.
“Our updated COVID-19 vaccine generates a robust immune response against the rapidly spreading EG.5 and FL 1.5.1 strains and reflects our updated vaccine’s ability to address emerging COVID-19 threats," Moderna President Stephen Hoge said in a statement.
Moderna also presented clinical data during June’s VRBPAC meeting demonstrating that its updated shot could also induce an immune response to the most important circulating XBB strains, according to the company’s news release.
The World Health Organization last week designated Eris as the newest variant of concern, suggesting that it harbors mutations that could increase its transmissibility, lead to worse clinical outcomes or allow it to evade the immune response primed by vaccination or previous infections.
As reported in WHO’s Aug. 9 advisory, Eris has a similar spike amino acid profile to XBB.1.5 though it carries an additional mutation. The global prevalence of Eris has been on the rise, reaching 7.6% by June 25 and spiking to 17.4% by July 23.
Nevertheless, the public health threat associated with Eris “is evaluated as low at the global level” despite showing signs of growth advantage and immune escape, according to WHO. So far, Eris has also not led to worse disease severity and WHO has not documented a correlation between the increasing prevalence of the subvariant and rising hospitalization rates.