Fall COVID shots will boost protection against latest subvariants, Moderna says

Moderna's updated COVID-19 vaccine provided a "significant boost" in people's neutralizing antibody levels against the latest omicron SARS-CoV-2 subvariants circulating in the US, that is, EG.5 and FL.1.5.1, according to a press release from the company.

The updated booster shot is expected to be authorized and rolled out in the coming weeks.

Moderna, which was reporting its takeaway from preliminary clinical trial data, did not release additional details of the study, including the number of trial participants or the relative increase of neutralizing antibody levels. But the announcement aimed to ease concerns about whether the fall booster will adequately match this season's variants.

"These new results, which show that 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 the press release.

The shots were designed against the previously reigning omicron subvariant, XBB.1.5. In June, an advisory panel for the Food and Drug Administration determined that a shot aimed at an XBB variant, particularly XBB.1.5, was the best choice for the 2023-2024 season.

Both EG.5 and FL.1.5.1 are in the XBB family, with EG.5 related to XBB.1.9.2 and FL.1.5.1 related to XBB.1.9.1. (Some of these subvariants have been given unofficial, mythological nicknames by a scientist on social media. Ars will only use the established Pango Lineage classification system endorsed by the World Health Organization and other major health organizations to describe variant lineages.)

According to the latest data from the Centers for Disease Control and Prevention, EG.5 is estimated to account for roughly 21 percent of circulating SARS-CoV-2 viruses, while FL.1.5.1 accounts for around 13 percent.

Pfizer also said that its XBB.1.5-targeted booster also spurred neutralizing antibodies against EG.5 in a mouse study, according to a report from Reuters.