Pfizer and BioNTech have commenced a Phase II clinical trial of an ‘enhanced’ Covid-19 messenger ribonucleic acid (mRNA)-based vaccine candidate, BNT162b5.

The next-generation bivalent vaccine, BNT162b5 comprises RNAs that encode improved prefusion spike proteins for the ancestral strain and Omicron variant of the SARS-CoV-2 virus. 

The randomised, active-controlled, observer-blind trial will analyse the safety, tolerability and immune response of the vaccine at a dose level of 30µg.

The trial in the US, which will not have a placebo, will enrol nearly 200 subjects aged between 18 and 55 years. 

These subjects should have previously received a booster shot of a US-authorised Covid-19 vaccine a minimum of 90 days before the first trial visit. 

Participants will be categorised based on the number of months from the last vaccine dose before entering the trial.

The enhanced spike protein encoded from the mRNAs in the vaccine was updated to boost immune response strength and breadth to offer better protection against Covid-19.

According to a press statement, Pfizer said: “This is the first of multiple vaccine candidates with an enhanced design which the companies plan to evaluate as part of a long-term scientific Covid-19 vaccine strategy to potentially generate more robust, longer-lasting, and broader immune responses against SARS-CoV-2 infections and associated Covid-19.”

Earlier this month, the US Food and Drug Administration approved Pfizer and BioNTech’s supplemental Biologics License Application for their Covid-19 vaccine, Comirnaty, for adolescents aged 12 to 15 years.

Comirnaty is said to be the first Covid-19 shot to receive FDA approval for adolescents.

Cell & Gene Therapy coverage on Clinical Trials Arena is supported by Cytiva.

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