Attributable to the continual emergence of recent immune evasive and more pathogenic variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), current coronavirus disease 2019 (COVID-19) vaccines have grow to be less effective in stopping infection. Consequently, Moderna has developed a novel bivalent vaccine that has recently been shown to elicit superior immune responses against these novel viral variants.

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The escape properties of the Omicron variant

Since its initial emergence at the tip of December 2019, SARS-CoV-2, which is the virus liable for causing COVID-19, has undergone extensive mutations. Lots of these mutant strains of SARS-CoV-2, particularly SARS-CoV-2 variants of concern (VOCs), are able to evading host immunity elicited by each vaccination and natural infection.

The SARS-CoV-2 Omicron VOC, for instance, was originally detected in November 2021 in Botswana, South Africa. Since then, Omicron has further evolved into several subvariants, a few of which include BA.1, BA.2, BA.3, BA.4, and BA.5.

Several studies have reported that Omicron and its sublineages are able to escaping neutralization by individuals who’ve received two doses of a messenger ribonucleic acid (mRNA) vaccine. Consequently, researchers sought to extend the potency of current COVID-19 mRNA vaccines against this variant by recommending a 3rd booster dose.

Despite these efforts, several studies have shown that three doses of current mRNA vaccines provide only partial protection against SARS-CoV-2 infection with the Omicron variant.  

Moderna’s bivalent Omicron booster vaccines

Moderna, which is an American biotechnology company that pioneered mRNA vaccine technology, has recently developed a bivalent COVID-19 vaccine booster dose able to overcoming a few of the limitations related to their initial COVID-19 vaccine formulation. More specifically, this bivalent vaccine comprises equal amounts of mRNAs that encode for each the ancestral SARS-CoV-2 and Omicron variant spike proteins.

Moderna is currently conducting a phase II/III trial geared toward evaluating the immunogenicity, safety, and reactogenicity of a 50 microgram (µg) dose of the bivalent vaccine candidate. Herein, researchers are assessing the efficacy of their novel vaccine in study participants who received a two-dose primary series, in addition to a 3rd booster dose of the Moderna mRNA-1273 vaccine a minimum of three months prior to the beginning of the study.

Taken together, a complete of 819 people have participated on this study thus far. Of those individuals, 437 study participants were assigned to receive the novel bivalent vaccine dose, whereas 377 received a second booster dose of the unique Moderna mRNA-1273 vaccine.

Each patient groups reported similarly mild opposed reactions, essentially the most frequent of which included pain on the injection site, fatigue, headache, myalgia, and joint stiffness. Importantly, no deaths nor opposed effects that required discontinuation from the study were reported.

Patients who received the bivalent booster dose exhibited mean neutralizing antibody titers of two,372.4 against the Omicron variant, which was comparable to the mean value of 1,473.5 in study participants who received mRNA-1273 boosters 28 days after immunization. This remained true in patients with a previous history of COVID-19.

Moreover, the bivalent booster vaccine successfully induced higher neutralizing antibody titers against the Omicron BA.4/BA.5 subvariants, in addition to the Alpha, Beta, Gamma, and Delta variants, no matter a previous SARS-CoV-2 infection. This superior antibody response was maintained for a minimum of three months following receipt of the bivalent booster vaccine dose. These vaccine responses were consistent in study participants over the age of 65, thus indicating that this high-risk group is effectively protected against infection with the Omicron variant.

The neutralizing activity of sera obtained from bivalent booster vaccine doses has also been tested against the BQ.11 strain of SARS-CoV-2, which is a novel variant that has been increasingly reported throughout the world. These findings indicate that this novel vaccine formulation has the potential to guard against other latest SARS-CoV-2 variants.

We’re pleased to see that each of our bivalent booster vaccine candidates offer superior protection against Omicron BA.4/BA.5 variants in comparison with our original booster, which is encouraging given COVID-19 stays a number one reason for hospitalization and death globally.”