Pfizer and its German partner BioNTech said their COVID-19 booster vaccine, adapted for Omicron’s BA.4 and BA.5 subvariants, generated a strong immune response and was well tolerated in human testing.
With the results, which the companies described as consistent with preclinical data, the partners are following up on human trial data previously missing from their successful regulatory approval filings.
In a joint statement Thursday, the companies said data from approximately 80 adult patients showed that the booster dose led to a significant increase in neutralizing antibody levels against the BA.4/BA.5 variants after one week.
They did not disclose the levels of antibodies generated in the preliminary analysis of the study.
The Omicron-specific shots, made by Pfizer and Moderna Inc, have already been given the go-ahead in several countries, including in the United States for adults and, more recently, for children as young as 5 years old.
Health regulators for the European Union and the United States already approved the improved injection last month, although data from human trials were not available at the time.
But they felt encouraged enough by the results of a human trial of a similar injection targeting the BA.1 subvariant and the established vaccine based on the original virus discovered in China in late 2019.
“While we await 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 -old people,” said Pfizer CEO Albert Burla.
While the European Medicines Agency has also authorized vaccines that target the BA.1 subvariant, the US Food and Drug Administration has focused its immunity response against the rapidly spreading Omicron variant only on injections adapted to BA.4/5.
Preliminary data on Thursday also showed that in the adults over 55 age group, the new bivalent injection elicited a better neutralizing antibody response against the Omicron BA.4/5 subvariant than the established injection based on the original form of the virus.