Pfizer/BioNTech Omicron vaccine shows strong response

US drugmaker Pfizer and German partner BioNTech SE said on Friday their Omicron-tailored shot targeting the BA.4/5 subvariants produced a strong antibody response in older adults than the original shot after one month.

In October, the companies had released data which showed the vaccine produced higher virus-neutralizing antibodies in humans after a week, but did not disclose the levels of antibodies produced in the study.

On Friday, the companies said data from roughly 36 individuals aged 55 years or older showed the booster dose led to a nearly four-fold increase in neutralizing antibody levels against the BA.4/5 variants after one month.

In the age group of 18 to 55, data showed that the new bivalent shot also triggered a better neutralizing antibody response against the BA.4/5 subvariants. However, results for this age group were compared with pre-booster levels and not the original vaccine.

Some experts caution that antibody readings do not translate directly into levels of protective immunity, and may not necessarily reflect how effective the booster shot is.

“This data doesn’t tell anything about whether or not this (four-fold) increase is clinically significant,” said Dr. Paul Offit, director of vaccine education center at the Children’s Hospital of Philadelphia.

Based on data from preclinical studies, Omicron-tailored shots made by Pfizer and rival Moderna Inc have already been approved in the United States for adults as well as for children as young as five years.

According to government data, around 26.3 million Americans had received the updated shot as of Nov. 2, with around 3.4 million of those getting the shot over the past week.