A mixed vaccine schedule where an injection of Pfizer’s Covid-19 vaccine is given four weeks after an AstraZeneca injection will produce better immune responses than giving another dose of AstraZeneca, a study from AstraZeneca said on Monday. Oxford.
The study, called Com-COV, compared mixed two-dose schedules of Pfizer and AstraZeneca vaccines and found that, regardless of their combination, they produced high concentrations of antibodies against the coronavirus spike protein.
The data supports the decision of some European countries to start offering alternatives to AstraZeneca as a second injection after the vaccine was linked to rare blood clots.
Comprehensive coverage of the coronavirus outbreak
Matthew Snape, the Oxford professor behind the trial, said the results could be used to give vaccine deployments flexibility, but were not important enough to recommend on their own a change any more. wide compared to clinically approved schedules.
“It is certainly encouraging that these antibody and T cell responses look good with the mixed schedules,” he told reporters.
“But I think your fault must remain, unless there is a very good reason for the contrary, to what has been proven,” he added, referring to the vaccination schedules at identical injection evaluated in clinical trials.
The highest antibody response was seen in people receiving two doses of Pfizer vaccine, with the two mixed schedules producing better responses than two doses of AstraZeneca vaccine.
An injection of AstraZeneca followed by Pfizer produced the best T cell responses, as well as a higher antibody response than Pfizer followed by AstraZeneca.
The results were for combinations of vaccines given four weeks apart to 830 participants.
Com-COV is also looking at mixed programs over a 12-week interval, and Snape noted that AstraZeneca’s vaccine was known to produce a better immune response with a longer interval between doses.
In Britain, authorities have suggested an 8-week gap between vaccine doses for those over 40 and a 12-week gap for other adults.
“Given the stable UK supply position, there is no reason to change vaccination schedules at this time,” England Deputy Chief Medical Officer Jonathan Van-Tam said , adding that data over a 12-week interval would influence future deployment decisions. program.
More than 80% of adults in Britain have now received one dose of the Covid-19 vaccine and 60% have had two injections.