Pfizer says Omicron-specific COVID vaccine generates a stronger response

Pfizer-BioNTech said Saturday that a trial of its two Omicron-modified COVID-19 vaccine candidates elicited a "substantially higher immune response" against Omicron BA.1 compared to the companies’ current COVID-19 vaccine.

Why it matters: The news comes in advance of a meeting of a key FDA advisory committee Tuesday to examine how the composition of COVID-19 vaccines should be modified as the virus continues evolving and vaccine protection wanes.

What they're saying: “As we’ve said since the early days of the pandemic, we will follow the science and adapt our own approaches as needed to help address COVID-19 as the virus evolves,” Pfizer CEO Albert Bourla said in a statement.

• "We believe we have two very strong Omicron-adapted candidates that elicit a substantially higher immune response against Omicron than we’ve seen to date."

The details: The companies tested a vaccine candidate that targets the spike protein of the Omicron BA.1 variant, as well as a "bivalent" vaccine candidate that combined its Omicron-adapted vaccine with its vaccine for the original COVID strain.

• The Omicron-adapted candidate given as a fourth booster dose increased neutralizing antibodies between 13.5 times and 19.6 times, depending on the dose administered.
• The "bivalent" vaccine candidate increased neutralizing antibodies between 9.1 times and 10.9 times against Omicron, depending on the dose administered.

Yes, but: Omicron has continued to evolve with new subvariants.

• Preliminary studies demonstrate both Omicron-adapted candidates neutralize the subvariants Omicron BA.4 and BA.5 to a lesser extent than they do for BA.1, the companies said.
• "We will therefore remain vigilant and are prepared to rapidly adapt our Omicron-adapted vaccine candidates to emerging sublineages if epidemiological and laboratory data suggest," Ugur Sahin, CEO and co-founder of BioNTech, said in a statement.