A redesigned version of Modernas Covid-19 boostershot seems to provide stronger protection against the omicron variant than the current vaccine, the company said in a press release on Wednesday.
Early Experimental results found that the bivalent vaccine – designed to target both the omicron variant and the original coronavirus strain in a single shot – led to an eightfold increase in neutralizing antibody levels, according to the company.
The updated vaccine also increased antibody levels against all other known variants of concern, it says.
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Moderna has called the omicron bivalent vaccine its “leading candidate” for the fall.
The new shot, called mRNA-1273,214, was tested in a phase 2/3 clinical study involving 437 people at 50 micrograms – the same dose given in the current booster shot.
The new shot was generally well tolerated, the company said, with side effects similar to those with a booster dose of the existing vaccine.
Moderna has only announced the test results in a press release; the data have not yet been made available to external researchers for review.
“We expect more lasting protection against variants of concern with mRNA-1273,214, making it our main candidate for a booster for the fall of 2022,” CEO Stéphane Bancel said in a statement.
Two omicron sub-variants, called BA.4 and BA.5, continue to gain ground in the United States
Omicron and its growing family of sub-variants have given a significant boost to the protection afforded by the existing booster shots from Moderna and Pfizer-BioNTech.
Moderna has tested updated versions of its booster shots that can be distributed across the country this fall, when immunity to previous shots is likely to begin to wane and Covid cases are expected to increase again.
In April, Moderna announced that another bivalent vaccine candidate – which combines a beta-variant-specific vaccine with the company’s original formula – generated a strong immune response to several variants of concern, including omicron. The beta variant, which was first discovered in 2020, was particularly good at avoiding immunity, but it has almost completely fallen out of circulation.
Dr. Anna Durbin, a vaccine researcher at Johns Hopkins University in Baltimore, said that the bivalent omicron vaccine “makes sense”, as a more specific target is needed to generate more antibodies that can specifically attack the omicron variant.
John Moore, professor of microbiology and immunology at Weill Cornell Medical College, said that Modern’s release on Wednesday shows that the omicron bivalent vaccine “may be marginally better” than the original vaccine, although he added that he needs to see all the data for to confirm.
It is also unclear, Moore added, whether the protection against the bivalent vaccine will actually be more durable, since the company only measured antibody responses after one month.
Based on the release, it is also uncertain whether the vaccine will provide significant protection against BA.4 and BA.5, two sub-variants that are spreading in the United States, said Dr. Isaac Bogoch, an infectious disease doctor at the University of Toronto.
The bivalent vaccine targets the original omicron variant. BA.4 and BA.5 share many similarities with the original variant, but also appear to have mutations that make them more transmissible.
The release is “useful,” but “we need more clinical data,” Bogoch said.
A vaccine that targets more than one strain in a single shot is not a new concept. This year’s flu shot, for example, is aimed at four flu strains.
Moderna said they plan to submit the data to the Food and Drug Administration “in the coming weeks,” hoping the new shot may be available late this summer.
On June 28, the FDA’s advisory committee will meet to discuss which strain or strains should be included in Covid booster shots this fall.
During a conversation with investors on Wednesday, Moderna said that the FDA has asked the company to join the meeting on June 28 to provide a “brief update” on the vaccine.
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