LONDON (UK) – Britain on Thursday started a trial to evaluate the immune responses generated if doses of the COVID-19 vaccines from Pfizer Inc and AstraZeneca Plc are combined in a two-shot schedule.
The British researchers behind the trial said data on vaccinating people from the two different types of coronavirus vaccines could provide an understanding of whether shots can be rolled out with greater flexibility around the world. They are expecting initial data on immune responses to be generated around June.
The trial will evaluate how the immune responses are after giving an initial dose of Pfizer vaccine followed by a booster of AstraZeneca’s, as well as vice versa, with intervals of 4 and 12 weeks.
The rollout of both the mRNA shot developed by Pfizer and Biontech and the adenovirus viral vector vaccine developed by Oxford University and AstraZeneca are currently being held in Britain, with a 12-week gap between two doses of the same vaccine.
It is expected more vaccines will be added to the trial when they are approved and rolled out.
Recruitment for the study will begin on Thursday, with over 800 participants expected to participate, the researchers said. That makes it much smaller than the clinical trials that have been used to determine efficacy of the vaccines individually.
The trial will not take into account the overall efficacy of the shot combinations, however, researchers will measure antibody and T-cell responses, in addition to monitoring any unexpected side effects.
Matthew Snape, an Oxford vaccinologist who is leading the trial, said initial results could inform vaccine deployment in the second half of the year.
“We will get some results through, we expect, by June or thereabouts that will inform the use of booster doses in the general population,” he told reporters.
The trial is looking to rope in people above the age of 50 who may be at higher risk than younger people and have not got any vaccination already.
AstraZeneca’s shot is also being tested by combining with Russia’s Sputnik V vaccine, and British drugmaker’s research chief has said more such studies on combining vaccines should be carried out.
