New Omicron Shots Elicit ‘Encouraging Responses’ in Humans, Pfizer Says

Preliminary results in 80 humans showed that Pfizer/BioNTech’s recently authorized Omicron vaccine substantially increased neutralizing antibodies against the BA.4 and BA.5 subvariants, the companies announced.

One week after administration, a single 30-µg booster dose of the bivalent shot produced similar levels of neutralizing antibodies for individuals ages 18 to 55 and those older than 55.

Individuals who received the companies’ monovalent vaccine had “more limited increases in the neutralizing antibody response” against the two subvariants, according to the release. Antibody levels were not disclosed in the release.

Pfizer/BioNTech said that early data showed that their bivalent vaccine — which was designed with components that target BA.4 and BA.5 along with the original strain — was well tolerated, “indicating a favorable safety profile, similar to that of the original vaccine.”

“While we expect more mature immune response data from the clinical trial of our Omicron BA.4/BA.5-adapted bivalent vaccine in the coming weeks, we are pleased to see encouraging responses just one week after vaccination in younger and older adults,” said Albert Bourla, PhD, chairman and CEO of Pfizer.

“These early data suggest that our bivalent vaccine is anticipated to provide better protection against currently circulating variants than the original vaccine and potentially help to curb future surges in cases this winter,” he added.

BA.4/BA.5-adapted bivalent vaccines from Pfizer/BioNTech and Moderna were authorized by the FDA in August based on immunogenicity data from mouse studies and support from clinical studies testing earlier bivalent vaccines that targeted the original Omicron variant.

“These preliminary findings are consistent with our preclinical data showing a substantial increase in the neutralizing antibody response against the Omicron sublineages BA.4 and BA.5,” said Ugur Sahin, MD, CEO and co-founder of BioNTech, in a statement. “The current dominance of BA.4/BA.5 and related sublineages, underscores the importance of our data and science-based approach to develop a vaccine which is adapted to these prevalent strains of the virus and make it available in a timely manner.”

The multicenter randomized controlled phase II/III trial has enrolled approximately 900 participants ages 12 and up who have received at least three doses of an authorized COVID-19 vaccine. Participants ages 18 and up were randomized to receive either a 30-µg or 60-µg booster dose of the bivalent vaccine, while those ages 12 to 17 were given a 30-µg booster.

“Among the participants, samples were equally stratified at baseline in each group between those who had a prior or current history of SARS-CoV-2 and those with no prior or current history of SARS-CoV-2,” the release noted.

Pfizer/BioNTech said additional findings on responses at 1 month will be released as soon as they are available “to support potential full licensure and global registration” of the bivalent vaccine.

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