Britain’s medical regulator will examine all the data from trials of the COVID-19 vaccine developed by Oxford and AstraZeneca, including which dosing regimen is best to use, the regulator’s chief executive said on Wednesday.
“Our regulatory review is all encompassing. We will look at all available data,” June Raine, chief executive of the Medicines and Healthcare products Regulatory Agency (MHRA), told lawmakers after a study showed the vaccine had efficacy of 62% for trial participants given two full doses, but 90% for a smaller sub-group given a half, then a full dose.
“Clearly, we have great interest into the possible reasons for the different doses having a different efficacy… readout,” she said.
“The position is we will look at every piece of evidence… part of that will be to examine with great rigour, the basis for the appropriate dosage regimen.”
ChAdOx1 nCoV-19, now known as AZD1222, was developed by Oxford University’s Jenner Institute, working with the Oxford Vaccine Group.
It uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold (adenovirus) virus that causes infections in chimpanzees and contains the genetic material of SARS-CoV-2 spike protein.
After vaccination, the surface spike protein is produced, priming the immune system to attack COVID-19 if it later infects the body.
The recombinant adenovirus vector (ChAdOx1) was chosen to generate a strong immune response from a single dose and it is not replicating, so cannot cause an ongoing infection in the vaccinated individual.