LONDON (Reuters) – Britain launched a trial Thursday to assess the immune responses generated when doses of the COVID-19 vaccines from Pfizer Inc and AstraZeneca Plc are combined in a dual schedule.
The British researchers behind the trial said data on vaccinating people with the two different types of coronavirus vaccines could help understand whether shots could be rolled out around the world with more flexibility. The first data on immune responses is expected to be generated around June.
The trial will examine the immune responses to an initial dose of Pfizer vaccine followed by a booster of AstraZeneca, and vice versa, at intervals of 4 and 12 weeks.
Both the mRNA shot developed by Pfizer and Biontech and the adenovirus viral vector vaccine developed by Oxford University and AstraZeneca are currently being rolled out in the UK, with a 12-week interval between two doses of the same vaccine.
More vaccines are expected to be added to the trial as they are approved and rolled out.
Recruitment for the study begins Thursday, with more than 800 participants expected to participate, the researchers said. That makes it much smaller than the clinical studies used to determine the efficacy of the vaccines individually.
The trial won’t assess the overall efficacy of the shot combinations, but researchers will measure antibody and T cell responses and monitor for any unexpected side effects.
Matthew Snape, an Oxford vaccineologist who is leading the trial, said the initial results could inform the deployment of vaccines in the second half of the year.
“We will, through what we expect to see by June or thereabouts, informing the use of booster doses in the general population,” he told reporters.
The trial aims to recruit people over 50 who may be at higher risk than younger people and who have not yet been vaccinated.
The AstraZeneca shot is also being tested in conjunction with Russia’s Sputnik V vaccine, and the UK drugmaker’s head of research has said more studies should be done on combining vaccines.
Reporting by Alistair Smout; Editing by Bill Berkrot