Pfizer and BioNTech have reported findings from a Phase II/III clinical trial of an Omicron BA.4/BA.5-adapted bivalent Covid-19 booster vaccine (Pfizer-BioNTech COVID-19 Vaccine, Bivalent [Original and Omicron BA.4/BA.5]). 

The randomised, multicentre, controlled trial enrolled nearly 900 healthy subjects aged 12 years and above in the US. 

These subjects had earlier received a minimum of three doses of a Covid-19 vaccine authorised for usage. 

In the trial, participants aged 18 years and above were given either a 30µg or 60µg booster dose of the Omicron BA.4/BA.5-adapted vaccine while subjects aged 12 to 17 years were given a 30µg dose. 

According to the findings, a 30µg dose of the vaccine offered a strong neutralising immune response a month after administration. 

In people who were given the bivalent vaccine, the immune responses against BA.4/BA.5 sublineages were significantly greater than the original vaccine of the companies.

Both vaccines also showed comparable safety and tolerability profiles.

The geometric mean titer (GMT) against Omicron BA.4/BA.5 was reported to be 606 in people aged 18 to 55 years, indicating a 9.5-fold increase following booster administration. 

In subjects aged above 55 years, a 13.2-fold increase in GMT from pre-booster levels was observed. 

The companies have submitted these findings to the US Food and Drug Administration (FDA) and soon intend to share them with the European Medicines Agency (EMA), as well as other health agencies globally. 

BioNTech CEO, co-founder, and professor Ugur Sahin said: “These data demonstrate that our BA.4/BA.5-adapted bivalent vaccine works as conceptually planned in providing stronger protection against the Omicron BA.4 and BA.5 sublineages. 

“In the next step, and as part of our science-based approach, we will continue to evaluate the cross-neutralisation of the adapted vaccine against new variants and sublineages.”

The latest development comes after Pfizer and BioNTech began a Phase I trial of a combination vaccine candidate for influenza and Covid-19.