A recent study from South Korea has shown that a mixed vaccination of AstraZeneca jab as first dose and Pfizer-BioNTech COVID-19 shot as second boosts the neutralising antibody levels by six times compared to two regular AstraZeneca doses.
A total of 499 medical workers participated in the study. Out of the 499 participants, 100 took mixed doses of AstraZeneca jab followed by Pfizer COVID-19 vaccine. While 200 participants took two doses of the Pfizer-BioNTech COVID-19 vaccine, the remaining individuals took two doses of the AstraZeneca jab.
All participants developed neutralising antibodies that prevent SARS-CoV-2, the virus which causes COVID-19 infection, from entering cells and replicating. The group which took the mixed vaccination had developed similar amounts of neutralising antibodies found in the group that received two Pfizer shots, but much greater than those who took two AstraZeneca shots, according to a Reuters report.
Earlier, a British study had shown similar results. According to the study, AstraZeneca shot followed by the Pfizer dose produced the best T-cell responses. The antibody response was also higher than that induced by taking Pfizer shot followed by the AstraZeneca jab.
The data backs the decision of several countries to offer alternatives to the AstraZeneca COVID-19 vaccine as a second shot. The countries had taken the decision after AstraZeneca vaccine was linked to recipients developing rare blood clots.
"The South Korean study also analysed neutralizing activity against major variants of concern," the Korea Disease Control and Prevention Agency (KDCA) said.
None of the three groups in the study displayed reduced neutralising activity against the Alpha variant of the coronavirus which was first identified in the United Kingdom. However, the neutralization titre did decrease by 2.5 to 6 fold against Beta, Gamma and Delta variants of the virus.
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