Moderna, Pfizer say updated Covid vaccines were effective against highly mutated BA.2.86 variant in trials
New Covid vaccines from Moderna and Pfizer produced a strong immune response against BA.2.86, a highly mutated omicron variant that health officials are watching closely, the companies said Wednesday.

Moderna said its updated shot produced an 8.7-fold increase in protective antibodies against BA.2.86 in a clinical trial. Pfizer separately said its jab generated protective antibodies against that strain and other fast-spreading variants of the virus in a trial on animals.

BA.2.86 has been detected in small numbers nationwide. The Centers for Disease Control and Prevention previously said the strain, also known as "Pirola," may be more capable of escaping antibodies from earlier infections and vaccinations, but new research also suggests that the variant may be less immune-evasive than feared.

Moderna, Pfizer and Novavax are slated to roll out new vaccines targeting another omicron strain called XBB.1.5 within weeks, pending potential approvals from the U.S. Food and Drug Administration.

The new trial results suggest that shots from Moderna and Pfizer will still be effective against newer variants of the virus as XBB.1.5 declines nationwide.

Last month, Pfizer also said its updated shot "effectively neutralized" the now-dominant EG.5, or "Eris," variant in a recent study on mice.

Moderna also released clinical trial data suggesting that its new shot provides protection against the Eris and another rapidly spreading strain called FL.1.5.1.

"Taken together with our previously communicated results showing a similarly effective response against EG.5 and FL.1.5.1 variants, these data confirm that our updated COVID-19 vaccine will continue to be an important tool for protection as we head into the fall vaccination season," said Moderna President Stephen Hoge in a statement.

New vaccines are set to arrive as Eris and other Covid variants fuel a rise in cases and hospitalizations across the country.

Covid hospitalizations jumped 18.8% during the week ending Aug. 19, and 87% over the past month, according to the latest data from the CDC. But those metrics remain below levels seen when a surge strained hospitals last summer.

Eris accounted for 21.5% of all cases in the U.S. as of Saturday, while FL.1.5.1 accounted for 14.5%, according to the latest data from the CDC.

Last week, the CDC indicated BA.2.86 has been found in four U.S. states, but it's still so rare that it's not listed as a standalone strain on the CDC's variant tracker.