Monday, November 29

Mixing Oxford and Pfizer jabs could provide greater protection

People who have been double-dosed with the Oxford-AstraZeneca vaccine could have a stronger immune response if they were given a different jab as a booster, a leading scientist has said.

Professor Matthew Snape from the Oxford Vaccine Group said the mix and match approach may result in additional protection against coronavirus.

He made the comments following the results of a clinical trial comparing the current UK strategy of giving two doses of either the AstraZeneca or Pfizer/BioNTech vaccines against a combination of the two jabs.

Results showed people who received the AstraZeneca vaccine first, followed four weeks later by a Pfizer dose, produced antibody levels nine times higher than those given two doses of the Oxford jab.

Meanwhile, one of the Oxford vaccine’s developers has said there is no evidence a third Oxford-AstraZeneca jab is needed at the moment – despite new research suggesting it restores peak immunity.

Research by the University of Oxford team that developed the vaccine has shown a booster at least six months after the second jab brings immunity levels back to their peak – and significantly increases antibody and T-cell levels to the virus, including variants.

But the director of the Oxford Vaccine Group, Professor Sir Andrew Pollard, said the priority should be ensuring people in other countries have had at least one dose.

Volunteers who were given Pfizer first and AstraZeneca second had antibody levels five times higher than those who received two doses of the Oxford vaccine. Two doses of the Pfizer jab produced the highest antibody levels, but the T-cell response was higher in people receiving the combination of vaccines.

Prof Snape, who led the Com-CoV study, said the combination gives an extra kick to the immune system. He said: When it comes to the coming winter, if a third dose was to be given, then these are really important data to inform which vaccines we should be using and which combinations we should be using.

From our study you have to be thinking that if you received AZ/AZ (for the first and second doses) then maybe there would be advantages in getting an RNA vaccine (Pfizer or Moderna) next. Another study, called Cov-Boost is currently testing combinations of booster shots for people who’ve received either two doses of the AstraZeneca or Pfizer vaccines.

Results are expected by September, in time for a booster campaign this autumn and winter, if it is needed.