Pfizer and BioNTech have submitted an application to the US Food and Drug Administration (FDA) for emergency use authorisation of their jointly developed Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine for children aged six months to four years.
If authorised, children in this age group would receive a primary series consisting of two 3µg doses of the original Pfizer/BioNTech COVID-19 vaccine followed by a third 3µg dose of the BA.4/BA.5-adapted bivalent vaccine.
The companies explained in a statement that ‘with the high level of respiratory illnesses currently circulating among children under five years-of-age, updated COVID-19 vaccines may help prevent severe illness and hospitalisation’.
The adapted vaccine is already authorised as a booster dose for ages five years and older in both the US and EU.
These applications were supported by safety and immunogenicity data from the Pfizer/BioNTech 30µg Omicron BA.1 adapted bivalent vaccine, as well as pre-clinical data which demonstrated a booster dose of the BA.4/BA.5-adapted vaccine generated a strong neutralising antibody response against Omicron BA.1, BA.2 and BA.4/BA.5 variants, as well as the original wild-type strain.
Professor Ugur Sahin, chief executive officer and co-founder of BioNTech, outlined in October that the companies had started a clinical trial to evaluate the BA.4/BA.5-adapted vaccine in children aged six months to 11 years, aiming to “offer all age groups the opportunity to immunise against Omicron variants and subvariants”.
To this end, an application to extend the BA.4/BA.5-adapted bivalent vaccine marketing authorisation in the EU to include children ages six to four years is also currently under discussion with the European Medicines Agency.
Pfizer and BioNTech’s bivalent vaccine contains mRNA encoding the original SARS-CoV-2 spike protein – present in the original Pfizer/BioNTech COVID-19 vaccine – together with mRNA encoding the spike protein of the Omicron BA.4/BA.5 sub variants.
The World Health Organization (WHO) recommended earlier this year that COVID-19 vaccines need to be reworked to ensure they are effective against Omicron and future variants.
Since the recommendations, vaccine manufacturers have focused on the development of variant specific boosters. Moderna announced in July the advancement of two bivalent candidates for autumn this year, based on different population health security strategies in different countries. mRNA-1273.214 contains the BA.1 Omicron strain, while mRNA-1273.222 contains the BA.4/BA.5 Omicron strain.