Administration of Pfizer Covid vaccine four weeks after vaccination with AstraZeneca will elicit a better immune response than administration of another dose of AstraZeneca. This is stated in a study by Oxford University, cited by Reuters.
The study, called Com-COV, compared mixed two-dose schedules of Pfizer and AstraZeneca vaccines and found that in any combination, they produced high concentrations of antibodies against the coronavirus spike protein. The data provides support for the decision of some European countries that have started offering alternatives to AstraZeneca as a second shot after the vaccine was linked to rare blood clots.
The highest antibody response was seen in people receiving two doses of Pfizer vaccine, with both mixed schedules producing better responses than two doses of AstraZeneca vaccine. An AstraZeneca shot followed by Pfizer produced the best T-cell responses, and also a higher antibody response than Pfizer followed by AstraZeneca. The results were for combinations of vaccines given at four-week intervals to 830 participants.
Matthew Snape, the Oxford professor behind the trial, said that the findings could be used to give flexibility to vaccine rollouts, but was not large enough to recommend a broader shift away from clinically approved schedules on its own.
As it was reported earlier, the European Medicines Agency (EMA) said there are “good scientific grounds” to suggest that mixing COVID-19 vaccines is safe and effective.
In April, the World Health Organization (WHO) did not recommend vaccination with coronavirus vaccines from two different manufacturers - to speed up the vaccination process.