Study results showed a bivalent booster targeting the BA.1 and BA.5 omicron strains of the coronavirus failed to raise antibody levels by more than Novavax’s current vaccine or a monovalent vaccine aimed solely at BA.1.
The trial tested the three shots in adults aged 18 to 64 years old who were previously vaccinated with three doses of Pfizer’s or Moderna’s COVID-19 vaccines. It sought to determine whether the two redesigned Novavax booster shots could raise antibodies against omicron by more than the company’s original version.
The booster shot aimed just at BA.1 did, raising antibody levels against that strain by more than the original candidate and meeting the study’s threshold for success. But the bivalent vaccine did not, nor did it perform better than the BA.1-targeting candidate.
Novavax’s statement did not contain specific data on how the reformulated shots performed against BA.5, but the company said neither produced a better immune response than its original prototype against that strain, which is currently the most prevalent in the U.S.
The vaccine company, which arrived on the U.S. market well behind Pfizer, Moderna and Johnson & Johnson, described the data as supportive of its existing vaccine and the “broad immune response” it generates.
“The data we've collected here supports the continued and future use of our current vaccines as a booster,” Filip Dubovsky, Novavax’s chief medical officer, said in a call with reporters Monday. “The study achieved its strain change endpoint, allowing for various vaccines to be pushed forward if they're eventually needed.”
“We saw no benefit demonstrated for the bivalent vaccine utilizing our technology,” he added. “This may be different from other vaccine technologies.”
Novavax’s shot uses a more traditional vaccine technology than do Pfizer’s and Moderna’s, which rely on messenger RNA to generate an immune response to the coronavirus.
The Centers for Disease Control and Prevention in October said the Novavax shot could be used as an initial booster following primary vaccination for those who cannot or will not receive Pfizer’s or Moderna’s vaccine.
But the focus has shifted to second booster shots, specifically the new omicron-targeting vaccines from Pfizer and Moderna. Uptake of those boosters has been slow in the U.S., while fewer than 50,000 people have received Novavax’s currently authorized vaccine.
Dubovsky noted in the call that the restriction on use of the shot as only an initial booster has limited its uptake.
It is unclear how Novavax will proceed with its omicron-targeting booster candidates. Dubovsky said the company will continue studying the shots and gather antibody levels against other variants.