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Moderna says its new bivalent COVID-19 vaccine booster is more effective against variants such as Omicron. Boston Globe/Getty Images
  • Moderna has said its updated COVID-19 vaccine booster protects better against several SARS-CoV-2 variants, including Omicron.
  • The booster was designed to target two variants—the original variant and the Beta variant.
  • The redesigned vaccine also remained more effective against the original, Beta, and Omicron variants six months after administration.
  • The findings from this trial will be used in the research and development of new boosters, and the results from experiments for a new booster are expected by late June 2022.

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The U.S. pharmaceutical company Moderna announced on Tuesday, April 19, 2022, that its updated mRNA COVID-19 booster had produced a better immune response in clinical trials against several SARS-CoV-2 variants, including Omicron and Delta.

The new booster candidate, called 1273.211, was formulated to help individuals evade infection from SARS-CoV-2, as well as prevent severe disease, and avoid hospitalization.

The preprint study was published on Research Square.

The booster is a type of vaccine scientists call “bivalent,” which works by stimulating an immune response against two different antigens via a single inoculation. As SARS-CoV-2 has continued to mutate, experts have been encouraging the development of multivalent boosters against the virus.

The bivalent or multivalent vaccine concept is not new — current annual flu vaccines are “quadrivalent,” meaning that they target four flu strains with one shot.

Moderna designed the new formula to target the Beta variant that surfaced in South Africa in July 2020, as well as the original variant of SARS-CoV-2. The boosters currently in use—from Moderna, Pfizer, and others—are based solely on that original variant.

The dominant SARS-CoV-2 variant, as of April 2022, is the Omicron subvariant BA.2.

The booster candidate, mRNA 1273.211, was tested n 895 people against the currently approved mRNA 1273 booster. Some participants received a 50 micrograms (µg) dose, the same amount of viral RNA as the current boosters. Some received a 100 µg dose.

The participants who received the 50-µg dose had a 2.20-fold increase in their neutralizing antibody titers against Omicron after 28 days. Six months later, the participants still had 2.15 times the antibodies acquired with the original Moderna booster.

The booster also offered better protection against the original, Beta, and Delta variants at the one-month mark.

There were no hospitalizations among trial participants who received the booster, and side effects were similar to the current Moderna booster.

Dr. John P. Moore, professor of microbiology and immunology at Cornell University, said that although the results were promising, he didn’t currently see a need for updated formulas based on these results.

“That two-fold median titer increase is statistically significant, but it needs noting that the overall titer range in the study groups is [more than] 300-fold. How biologically important is the median 2-fold increase? Not very, in my view, and not enough to justify the costs and logistical hassles of rolling out a different vaccine composition,” he told Medical News Today.

A good way to look at the results, New York University microbiology professor Dr. Nathaniel Landau told MNT, is to see it as the “proof of principle” study it is, which “supports the concept of a bivalent mRNA vaccine”.

Dr. Jacqueline Miller, senior vice president of the Infectious Diseases Department at Moderna, said the company did not plan to file for authorization for 1273.211, but it would submit this data to the FDA to work on future vaccine candidates that target Omicron, as per Reuters.

Moderna has been developing and is currently collecting trial data on an Omicron-specific booster and a bivalent booster, mRNA-1273.214, that combines an Omicron-specific vaccine and the original vaccine. The company says they expect to release the data from this testing in the second quarter of 2022.

A significant difference between the mRNA 1273.211 and mRNA 1273.214 boosters is the number and type of mutations they target.

mRNA 1273.211 was based on the Beta SARS-CoV-2 variant, targeting nine of its spike protein mutations. mRNA 1273.214, in turn, is based on Omicron, addressing 32 of its spike protein mutations. mRNA 1273.211 targets just four protein spike mutations found in Omicron, since it is based on an older variant, Beta.

“The increase in titer against Omicron was minor [in mRNA 1273.211], to be expected because the vaccine doesn’t have the authentic Omicron spike (It just has four of the many mutations in Omicron),” said Dr. Landau.

Dr. Moore noted that Moderna’s trial data on mRNA 1273.211 are “essentially legacy studies from early 2021 when Beta was ‘a thing’ because of its NAb [neutralizing antibody] resistance. Now, Beta is very much not a thing, so there is essentially no chance that a Beta-based vaccine will be rolled out here.”

Experts are now looking forward to the results for mRNA 1273.214.

“The vaccine of greater interest is the one being studied in the version [mRNA 1273.214 ] currently underway with the real Omicron spike. This study suggests that it’s going to be successful. An Omicron booster is just what’s needed,” said Dr. Landau.