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A study in South Korea found that a mixed COVID-19 vaccination of AstraZeneca followed by an injection of Pfizer resulted in a six-fold increase in neutralizing antibody levels compared to two doses of AstraZeneca.
The study involved 499 medical workers: 100 received mixed doses, 200 received two doses of the Pfizer / BioNTech vaccine, and the rest received two AstraZeneca vaccines.
All of them showed neutralizing antibodies, which prevent the virus from entering cells and replicating, and the result of the mixed vaccination plan showed similar amounts of neutralizing antibodies found in the group that received two injections of Pfizer.
The research also looked at neutralizing activity against the most interesting major variants, the Korea Disease Control and Prevention Agency (KDCA) said.
Neither group demonstrated reduced neutralizing activity against the alpha variant, first identified in the UK, but the degree of neutralization decreased between 2.5 and 6 times against beta, gamma and delta, first detected in South Africa, Brazil and India, respectively.
A British study conducted last month showed similar results: an injection of AstraZeneca followed by Pfizer produced the best T cell responses and a higher antibody response than Pfizer followed by AstraZeneca.
The data supports the decision of several countries to offer alternatives to AstraZeneca as a second injection after the vaccine has been linked to rare cases of thrombi, and in March, some European countries decided to suspend its use in certain groups of people. This has left many people partially vaccinated, unless they switch to a different brand for their second dose.
In May, researchers from the Carlos III Health Institute in Madrid announced the results of the CombiVacS test. The study found a strong immune response in people who received the Pfizer vaccine 8 to 12 weeks after receiving a dose of the Oxford-AstraZeneca vaccine. There was no direct comparison with people who received two doses of the same vaccine, but the authors found that in lab tests, those who received the combination produced 37 times more neutralizing antibodies against SARS- CoV-2 and 4 times more SARS, 2 specific immune cells called T cells, than people who received a single dose of Oxford-AstraZeneca Injection.
End of June, more results showing a similar effect. One study observed 340 health workers who received two doses of Pfizer-BioNTech vaccine or a first injection of Oxford-AstraZeneca vaccine followed by a dose of Pfizer-BioNTech. Both regimens elicited an immune response that included neutralizing antibodies and T cells.
A third study, conducted by researchers at the University of the Saar in Homburg, Germany, found that the mixed diet was more effective in triggering an immune response than two injections of Oxford-AstraZeneca. It was as good or better than two shots of Pfizer – BioNTech. And on June 25, the team behind the UK trial, known as the Com-COV study, posted a preprint online showing that a good immune response was achieved regardless of the order. in which both vaccines were administered.
Combination vaccines could also be used to prevent launches from stalling due to supply issues with a particular formula.
(With information from Reuters)
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