A study conducted by the Korea Disease Control and Prevention Agency showed that mixing AstraZeneca and Pfizer Covid-19 vaccination is six times more effective in neutralizing antibody levels than two AstraZeneca shots, reported Reuters on July 26.
The South Korean study was conducted to test the efficacy of mixing vaccine doses against Coronavirus variants, namely the Alpha, Beta, Gamma and Delta variants.
499 medical workers participated in the study, out of which 100 received mixed vaccine doses— first shot being AstraZeneca and second Pfizer, 200 received two doses of the Pfizer/BioNTech vaccine, and 199 received two doses of the AstraZeneca vaccine.
The results showed that while all variations of vaccine doses exhibited neutralized antibodies, mixing both Pfizer and AstraZeneca vaccines showed the same levels of neutralizing antibodies as compared to receiving two doses of the Pfizer/BioNTech vaccine.
A similar British study called Com-COV, conducted by the University of Oxford in June produced the same results and noted that an AstraZeneca shot followed by a Pfizer shot produces a higher antibody response than receiving two AstraZeneca shots.
The results of the study provide further data for countries to greenlight mixing vaccine shots, as the second dose of AstraZeneca has been linked to causing rare blood clots. While the link has been established, the risk of a blood clot after receiving the second dose of AstraZeneca is one in 600,000.
The Korea Disease Control and Prevention Agency also said that the study analysed the vaccine's neutralizing effects on Coronavirus variants that are of major concern.
The results showed that while none of the participant groups showed neutralizing activity against the Alpha variant, a six-fold increase in efficacy against the Beta, Gamma and Delta variant were detected.