A South Korean study has found that taking an AstraZeneca vaccine shot followed by a Pfizer-BioNTech vaccine boosted COVI-19 antibody levels six times more than receiving two Astra-Zeneca doses, as some governments give the green light to mix COVID-19 vaccine shots for extra protection against the virus.
Forbes reports that the study (of which the research details have not yet published) was conducted by the Korea Disease Control and Prevention Agency (KDCA), and it took a look at the effects of mixing certain vaccine doses and vaccine efficacy against coronavirus variants Alpha, Beta, Gamma and Delta.
The study involved 499 medical workers — 100 receiving mixed doses, 200 taking two doses of the Pfizer/BioNTech shot and the remainder getting two AstraZeneca shots.
All showed neutralising antibodies, which prevent the virus from entering cells and replicating, and the result of the mixed schedule of vaccines showed similar amounts of neutralising antibodies found from the group that received two Pfizer shots.
TimesLIVE said a British study led by Oxford University last month showed similar results — an AstraZeneca shot followed by Pfizer produced the best T-cell responses, and a higher antibody response than Pfizer followed by AstraZeneca.
The data provides further support for the decision of several countries to offer alternatives to AstraZeneca as a second shot after the vaccine was linked to rare blood clots.
The South Korean study also analysed neutralising activity against major variants of concern, the Korea Disease Control and Prevention Agency (KDCA) said.
None of the groups demonstrated reduced neutralising activity against the Alpha variant, first identified in Britain, but the neutralisation titre decreased by 2.5 to 6 fold against Beta, Gamma and Delta, first detected in SA, Brazil and India respectively.
Forbes notes that Pfizer has created a booster shot to target the Delta variant, trials began a week ago. Moderna will also be developing a booster shot, with trial results expected by September.
Sunday Times article – Mixed AstraZeneca-Pfizer shot boosts Covid-19 antibody level, study finds
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