LONDON (Reuters) – Britain on Thursday launched a trial to assess the immune responses generated when 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 vaccination of people with the two different types of coronavirus vaccines could help understand whether shots with greater flexibility could be rolled out around the world. Initial data on immune responses are expected to be generated around June.
The trial examined the immune responses of an initial dose of Pfizer vaccine, followed by an AstraZeneca booster, as well as vice versa, at 4- and 12-week intervals.
Both the mRNA shot developed by Pfizer and Biontech, and the adenovirus viral vector vaccine developed by the University of Oxford and AstraZeneca, are currently being rolled out in the UK, with a twelve-week gap between two doses of the same vaccine. .
More vaccines are expected to be added to the trial once approved and rolled out.
The recruitment for the study begins Thursday, with more than 800 participants expected to participate, the researchers said. This makes it much smaller than the clinical trials used to determine the efficacy of the vaccines individually.
The trial will not assess the overall efficacy of the shot combinations, but researchers will measure antibody and T cell responses, as well as monitor for unexpected side effects.
Matthew Snape, a vaccine expert at Oxford who is leading the trial, said the initial results could inform the deployment of vaccines in the second half of the year.
“We are expected, by June or so, to get some results that will inform the use of booster doses in the general population,” he told reporters.
The trial is aimed at recruiting people over 50 who are at higher risk than younger people and who have not yet been vaccinated.
The shot of AstraZeneca is also being tested in combination with the Russian Sputnik V vaccine, and the research chief of the British drug manufacturer said more studies on the combination of vaccines should be done.
Reporting by Alistair Smout; Edited by Bill Berkrot