Pfizer sends 'enhanced' COVID shot to clinic under strategy for next generation of vaccines

Pfizer just raised the stakes of the COVID-19 vaccine business. The Big Pharma has launched a midstage trial of the first in a planned series of next-generation, variant-busting COVID-19 vaccines that the drugmaker is working on with BioNTech.

The bivalent shot, dubbed BNT162b5, consists of RNAs that encode enhanced prefusion spike proteins for both the original strain of SARS-CoV-2 and the omicron variant that is prevalent worldwide. The enhanced spike protein has been modified with the aim of increasing the magnitude and breadth of the immune response to COVID-19, Pfizer said in a statement Tuesday.

The phase 2 study will see the vaccine administered as a 30-microgram booster dose to around 200 participants in the U.S. aged between 18 and 55 years old. The trial will not include a placebo cohort.

BNT162b5 is the first of a number of vaccine candidates with an enhanced design that Pfizer and BioNTech plan to evaluate as part of their long-term COVID-19 vaccine strategy to provide more robust and longer-lasting immune responses, Pfizer said.

It’s not the first omicron-adapted bivalent vaccine they have put into the clinic, however. Last month, they posted immune data from a phase 2/3 study of another bivalent candidate. Unlike the next-generation vaccine, which features enhanced spike proteins, this existing bivalent shot was a combination of the approved Pfizer-BioNTech COVID-19 vaccine and a candidate targeting the spike protein of the omicron variant.

The trial results last month showed that neither dose cohort of that vaccine met the bar for super superiority. But the results were still enough to reach the lower end of the pre-specified criterion for superiority, Pfizer noted.

Earlier in June, Moderna posted results from its own bivalent omicron-busting vaccine, which the biotech said demonstrated a superior neutralizing antibody response against the variant.

Companies are racing to come up with variant-busting COVID vaccines as efficacy wanes with the previously authorized and approved shots. The FDA also asked vaccine makers like Moderna and Pfizer to update their booster shots for the fall campaign to add omicron BA.4 and BA.5 spike protein components to ensure they can tackle the latest circulating variants.