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Mixed schedules involving the Pfizer/BioNTech and Oxford/AstraZeneca vaccines generate strong immune response against the SARS-CoV2 spike IgG protein, according to findings from the Com-COV study led by the University of Oxford.
In a paper published on the Lancet pre-print server, researchers report that both mixed schedules (Pfizer/BioNTech followed by Oxford/AstraZeneca, and Oxford/AstraZeneca followed by Pfizer/BioNTech) induced high concentrations of antibodies against the SARS-CoV2 spike IgG protein when doses were administered 4 weeks apart.
The trial recruited 830 volunteers aged 50 and above from eight National Institute for Health Research (NIHR) supported sites in England to evaluate the four different combinations of prime and booster vaccination.
In April, the researchers expanded the programme to include the Moderna and Novavax vaccines in a new study, run across nine NIHR supported sites and backed through funding from the Vaccines Taskforce and the Coalition for Epidemic Preparedness Innovations.
The six new ‘arms’ of the trial each recruited approximately 175 candidates, adding a further 1070 recruits into this programme.
The latest results show that the order of vaccines makes a difference, with the Oxford/AstraZeneca followed by Pfizer-BioNTech schedule inducing higher antibodies and T-cell responses than Pfizer-BioNTech followed by Oxford/AstraZeneca.
Both schedules inducing higher antibodies than the licensed, and highly effective standard two-dose Oxford/AstraZeneca schedule. The highest antibody response was seen after the two-dose Pfizer/BioNTech schedule, and the highest T cell response with Oxford/AstraZeneca followed by Pfizer/BioNTech.
