As for autumn, another bivalent candidate for the mRNA-1273.214 bivalent booster is also being developed, but only the BA.4/5 clinical trial demonstrated significantly higher titers against the strain.
The vaccine is based on a version of the spike protein that the companies hope will offer better and broader protection against the virus.
A new version of the COVID-19 vaccine is being studied in a phase 2 trial jointly run by Pfizer and BioNTech. It is hoped that it will better protect against the virus.
The Pfizer-BioNTech COVID-19 vaccine, BNT162b5, includes RNAs encoding ‘enhanced’ prefusion spike proteins for the SARS-CoV-2 wild-type strain and an Omicron variation, in an attempt to increase the magnitude and breadth of the immune response.
Around 200 participants aged 18 to 55 will be recruited for a US-based study in which the vaccine candidate will be evaluated. Following an enrollment period, participants will be randomly assigned to subgroups based on the number of months since their last dose. A placebo will not be used in the study.
The companies said BNT162b5 is the first of multiple vaccine candidates with an enhanced design, representing their long-term COVID-19 vaccine strategy to overcome the relatively short-lived immune response seen with their first-generation vaccine, BNT162b2.
The trial’s commencement comes as vaccine developers are beginning to develop new versions of their vaccines in response to Omicron, following the US Food and Drug Administration’s (FDA) recommendation to continue developing Omicron-targeting formulations, with the aim of making them available in autumn this year.
Pfizer and BioNTech submitted Omicron-adapted bivalent COVID-19 vaccine to the European Medicines Agency (EMA) earlier in July, based on the BA.1 sub-lineage.
The Omicron-adapted bivalent vaccine candidate produced superior immune responses against Omicron BA.1 in phase 2/3 tests following positive results from a phase 2/3 trial.
Moderna announced positive data in July for its bivalent BA.1 booster candidate, mRNA-1273.214, showing a significantly higher neutralising antibody response against Omicron subvariants BA.4 and BA.5 compared to mRNA-1273, regardless of prior infection status or age.
However, the mRNA-1273.214 bivalent booster is the only candidate that has demonstrated significantly higher titers against the BA.4/5 strain in a clinical trial.