The data is encouraging as it shows that the bivalent booster shots, which were updated to match the BA.4 and BA.5 versions of the omicron variant and rolled out in September, offer protection against newer coronavirus variants. awaiting a possible winter wave of cases.
Moderna also said a preliminary analysis with a small number of subjects showed that the antibodies generated by the bivalent booster lost some potency against the challenging and fast-growing BQ.1.1 subvariant — but were still able to block it. BQ.1.1 makes up about a quarter of cases in the United States, according to the Centers for Disease Control and Prevention.
“Evolution is a dangerous thing to bet against. The virus continues to surprise us and we need to be ready to update the vaccine,” said Stephen Hoge, president of Moderna. But he added that he was encouraged by the high antibody levels caused by the booster injection as the country enters winter.
“I think we’re optimistic that this BA.4/BA.5-containing bivalent will be enough to get us through it,” Hoge said.
Moderna’s announcement will intrigue scientists thinking about future booster strategies because the makers of both messenger RNA coronavirus vaccines have now presented convergent results showing that their bivalent injections produce a stronger response than their original formulations.
But the news is a bit of an artificial comparison to the general public because those original boosters are no longer available. The decision to switch was made over the summer to ensure sufficient supply to vaccinate people with the updated shots ahead of a potential winter wave of cases.
It is also unclear whether the data will help fuel public interest in the boosters. Only about 10 percent of people age 5 and older in the United States have been given a bivalent booster, according to CDC data.
To measure the effect of the additional injection, scientists compared the virus-inhibiting antibodies in the blood of 511 people, before and after the bivalent booster or the original. What these kinds of lab experiments can’t predict is how well or for how long the higher antibody levels will protect people from infections or serious illness. Most scientists expect that the boosters will help strengthen protection against the worst outcomes, but not provide quite as robust protection against infection.
Moderna reported that its bivalent booster produced five to six times as many antibodies as the older booster. That’s a stronger advantage than the effects of a previous bivalent booster tuned to fight the BA.1 variant. But some scientists have questioned whether differences between the two groups of people who received each type of injection may partly account for some of the benefit.
In contrast, Novavax, a latecomer to the vaccine race, presented data last week suggesting that a bivalent booster from its injection of the omicron BA.1 subvariant offered no advantage over its original booster.
The company did not present data on a BA.4/BA.5-containing bivalent vaccine, but argued that the original injection could continue to provide protection, rather than updating the formula. It is not clear why there are different results. Novavax’s medical director, Filip Dubovsky, said last week that the company’s injection could trigger a broader response to the variants, which is then amplified by repeated boosts of the older formulation. Unlike the commonly used messenger RNA vaccines from Pfizer-BioNTech and Moderna, the Novavax Injection is a protein-based vaccine with an added substance called an adjuvant designed to revitalize the immune system.
Novavax has said it may update its listing if regulatory authorities require it.
“We’re kind of ready to respond to whatever it takes,” Dubovsky said. “But we actually think we have a case that holding onto what we have now and seems to be working now is the way to go into the future.”