Trial in Britain to test the combination of Pfizer and AstraZeneca vaccines in a two-dose schedule

LONDON (Reuters) – Britain on Thursday launched a trial to assess the immune responses generated if doses of Pfizer Inc and AstraZeneca Plc’s COVID-19 vaccines are combined in a two-dose schedule.

British researchers behind the trial said data on immunizing people with the two different types of coronavirus vaccines could help understand whether vaccines can be deployed with greater flexibility around the world. The first data on immune responses should be generated around June.

The trial will examine immune responses to an initial dose of Pfizer vaccine followed by a booster AstraZeneca, and vice versa, with intervals of 4 and 12 weeks.

The mRNA vaccine developed by Pfizer and Biontech and the adenovirus viral vector vaccine developed by the University of Oxford and AstraZeneca are currently being deployed in Britain, with a 12-week interval between two doses of the same vaccine. .

It is expected that more vaccines will be added to the trial when they are approved and deployed.

Recruitment for the study begins Thursday, with more than 800 participants expected, the researchers said. This makes it much smaller than the clinical trials that have been used to determine the effectiveness of individual vaccines.

The trial will not assess the overall effectiveness of the shot combinations, but researchers will measure antibody and T cell responses, and watch for unexpected side effects.

Matthew Snape, an Oxford vaccinologist who is leading the trial, said the first results could inform the vaccine rollout in the second half of the year.

“We will get, we expect, some results by June or so that will inform the use of booster doses in the general population,” he told reporters.

The trial seeks to recruit people over the age of 50 who may be at greater risk than younger people and who have not yet been vaccinated.

AstraZeneca’s shot is also being tested in combination with Russia’s Sputnik V vaccine, and the UK drugmaker’s head of research has said more studies on the vaccine combination should be conducted.