Covid-19: What are the effects of administering two different vaccines? Preliminary data from Oxford study might have the answer

Mixing coronavirus vaccine: Earlier this year, researchers at the University of Oxford had launched a study called Com-COV to look into whether doses of COVID vaccines produced by Pfizer-BioNTech and Oxford-AstraZeneca could be alternated. Now, the preliminary data from the study has been released, and it shows that mixed schedules, i.e. those schedules in which people are administered the first jab of vaccine, followed by a second jab of another vaccine, led to more frequent occurrence of mild-to-moderate reactions as compared to the standard schedules where individuals are administered two doses of the same vaccine.

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The researchers shared the results in a peer-reviewed Research Letter that was published in the reputed journal The Lancet. They said that they administered both variations of mixed schedules – Oxford-AstraZeneca vaccine after Pfizer-BioNTech one and vice versa – at an interval of four weeks, and in both of them, it was found that after the administration of the second shot, there were more frequent reactions as compared to the standard way of administering doses.

However, they also asserted that any adverse reactions that were experienced by the participants were only for a short duration and there were no other safety concerns either.

A statement by the University of Oxford quoted the trial’s chief investigator Matthew Snape as saying that this only formed a secondary part of the study, but the researchers found it important to release this data due to the fact that several countries were considering the mixed schedule of vaccination. He added that the data showed that if mixed schedules were undertaken, there could be a significant increase in absences on days after the immunisation, something that the countries must consider when they undertake the inoculation of healthcare workers.

Dr Snape further said that the researchers did not have any safety concerns or signals, nor did they know yet about the impact of this schedule on the immune response. They are looking to release data in this regard in the upcoming months.