Pfizer and BioNTech have reported that two Omicron-adapted Covid-19 vaccine candidates demonstrated a greater immune response against Omicron BA.1 as against their existing vaccine in a Phase II/III trial.
The trial analysed the tolerability, safety and immunogenicity of the booster dose of the two vaccine candidates: one monovalent and the other bivalent, a combination of the companies’ Covid-19 vaccine and a candidate that acts on the Omicron BA.1 variant of concern’s spike protein.
Data found that the immune response was seen across 30µg and 60µg investigational dose levels.
Pfizer chairman and CEO Albert Bourla said: “Based on these data, 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.
“We look forward to discussing these data with the scientific community and health authorities so we may rapidly introduce an Omicron-adapted booster as soon as possible if authorised by regulators.”
The two vaccine candidates were studied in a total of 1,234 subjects aged 56 years and above.
For the monovalent 30µg and 60µg vaccines, the geometric mean ratios (GMRs) were 2.23 and 3.15, respectively, as against the current Covid-19 vaccine.
The GMRs for the bivalent 30µg and 60µg dose levels were 1.56 and 1.97, respectively.
In the trial, it was found that the monovalent Omicron-adapted vaccine in these dose levels achieved a lower bound 95% confidence interval for GMR of >1.5.
One month after administration, a booster dose of the monovalent candidates increased neutralising geometric mean titers (GMT) against Omicron BA.1 13.5 and 19.6-fold, which was above pre-booster dose levels.
A booster dose of the bivalent candidates showed a 9.1 and 10.9-fold rise in neutralising GMTs against Omicron BA.1.
In subjects, who were given one or the other Omicron-adapted vaccine, both vaccine candidates were found to be well-tolerated.
Pfizer and BioNTech plan to share these data with the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).
In a previous development, Pfizer and BioNTech reported topline findings from a Phase II/III clinical trial, where a third 3µg dose of their Covid-19 vaccine induced a robust immune response in children aged six months to under five years.