The data are encouraging because they show that the bivalent booster shots, which were updated to match the BA.4 and BA.5 versions of the omicron variant and began rolling out in September, offer protection against newer coronavirus variants ahead of a possible winter wave of cases.
Moderna also said that 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 could still block it. BQ.1.1 accounts for 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 must be ready to update the vaccine, says Stephen Hoge, Moderna’s president. But he added that he was encouraged by the high antibody levels induced by the booster shot as the country heads into winter.
“I think we’re optimistic that this BA.4/BA.5-containing bivalent is going to be sufficient to get us through,” Hoge said.
Moderna’s announcement will fascinate researchers thinking about future booster strategies because the makers of both messenger RNA coronavirus vaccines have now presented converging results showing that their bivalent shots trigger a stronger response than their original formulations.
But the news is a bit of an artificial comparison to the general public because the original boosters are no longer available. The decision to switch was made over the summer to ensure enough 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 ignite public interest in the boosters. Only about 10 percent of people 5 and older in the United States has received a bivalent booster, according to CDC data.
To measure the effect of the extra shot, researchers compared the virus-blocking antibodies in the blood of 511 people, before and after the bivalent booster or the original. What these types of laboratory experiments cannot predict is how well or how long the higher antibody levels will protect people from infection or serious illness. Most researchers expect that the boosters will help strengthen protection against the worst outcomes, but will not provide as robust protection against infections.
Moderna reported that its bivalent booster created five to six times the level of antibodies compared to the older booster. It is a stronger advantage than the effect of a previous bivalent booster tuned to combat the BA.1 variant. But some researchers have questioned whether differences between the two groups of people who received each type of shot may be partially responsible for some of the benefits.
In contrast, Novavax, a latecomer to the vaccine race, presented data last week suggesting that a bivalent booster of the shot that included the omicron BA.1 subvariant did not provide an advantage over the original booster.
The company did not present data on a BA.4/BA.5-containing bivalent vaccine, but argued that its original shot could continue to offer protection, rather than updating the formula. It is unclear why there are divergent results. Novavax’s chief medical officer, Filip Dubovsky, said last week that the company’s shot can induce a broader response to the variants, which is then boosted by repeated boosts of the older formulation. Unlike the widely used messenger RNA vaccines from Pfizer-BioNTech and Moderna, the Novavax shot is a protein-based vaccine with an added substance called an adjuvant designed to rewire the immune system.
Novavax has said it may update the image if required by regulatory agencies.
“We’re kind of ready to respond to what’s required,” Dubovsky said. “But we actually think we have a case that sticking with what we have now, and seems to be working now, is the way to go into the future.”