Moderna has reported latest clinical findings where its bivalent (Omicron) Covid booster candidate, mRNA-1273.214 stimulated potent neutralising antibody responses against the BA.4 and BA.5 subvariants of Omicron.

A 50µg booster dose of mRNA-1273.214 showed such activity a month following dosing in already vaccinated and boosted subjects, irrespective of previous infection.   

Furthermore, the vaccine provided a 5.4-fold enhanced neutralising titers against BA.4/BA.5 above baseline in all subjects irrespective of previous infection and a 6.3-fold in the subset of seronegative subjects. 

Compared to priorly reported neutralising titers against BA.1, nearly three-fold reduced neutralising titers against BA.4/BA.5 were reported.

Neutralising geometric mean titers (GMT) against BA.4/BA.5 A month after an mRNA-1273.214 booster were 941 and 727 in all subjects and seronegative participants, respectively. 

The latest findings supplement data from the ongoing Phase II/III clinical trial in nearly 800 subjects. 

According to the trial data, a 50µg booster dose of mRNA-1273.214 achieved all pre-specified primary endpoints, including superiority in neutralising antibody GMT against Omicron (BA.1), versus a 50µg booster dose of the prototype booster, mRNA-1273. 

In addition, the bivalent booster was found to be well-tolerated, with a reactogenicity and safety profile in line with the prototype booster. 

Based on these data, the company will make regulatory submissions seeking an update to the composition of the booster vaccine to mRNA-1273.214.

Moderna CEO Stéphane Bancel said: “In the face of SARS-CoV-2’s continued evolution, we are very encouraged that mRNA-1273.214, our lead booster candidate for the fall, has shown high neutralising titers against the BA.4 and BA.5 subvariants, which represent an emergent threat to global public health. 

“We will submit these data to regulators urgently and are preparing to supply our next generation bivalent booster starting in August, ahead of a potential rise in SARS-CoV-2 infections due to Omicron subvariants in the early fall.”

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