Moderna’s updated Covid booster appears to increase the immune response to omicron subvariants BA.4 and BA.5, as well as another subvariant, called BQ.1.1, that's gaining ground in the United States, the company said in a release Monday.
The results are based on blood samples taken from 511 adults who got the updated booster, which targets BA.4 and BA.5, along with the original coronavirus strain, in a single shot.
The volunteers were compared to another group of participants who got a booster dose of the first iteration of the company's vaccine, which only targets the original coronavirus strain.
In people who got the updated booster, neutralizing antibodies against BA.4 and BA.5 were about fivefold higher in those with a previous Covid infection and sixfold higher in those without a documented infection, the company said.
Moderna's results, announced in a news release, have not been published in a peer-reviewed journal or reviewed by outside scientists.
The preliminary results are “helpful,” especially as new variants emerge, said Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto.
But the data still don't answer key questions: “Do these vaccines bring back durable protection against infection and onward transmission of SARS-CoV-2, and if so, for how long?” he said.
Moderna also said an additional analysis of 40 people found the updated booster demonstrated “robust neutralizing activity” against the subvariant BQ.1.1, though the response wasn’t as strong as what was seen against BA.4 and BA.5.
BQ.1.1 and a sister subvariant, called BQ.1, have recently gained ground in the U.S., making up about 45% of all new Covid cases as of Saturday, according to the Centers for Disease Control and Prevention.
Earlier this month, Pfizer and BioNTech said their updated booster shot generated a stronger immune response against BA.4 and BA.5 compared with their original Covid vaccine.
Moderna said its results build on data published in the New England Journal of Medicine, which found an earlier version of its updated booster produced a strong immune response against the original omicron strain, called BA.1, as well as BA.4 and BA.5. That version of the booster is not available in the U.S.