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Publication
30.07.2021

Mix-and-match Vaccine Against COVID-19 Tested: Immune Response Stronger Than After Two Doses of Astrazeneca Vaccine

For safety reasons, the Standing Committee on Vaccination (STIKO) in Germany recommends that anyone under the age of 60 who initially received a vaccine from AstraZeneca should be given an mRNA vaccine at their second appointment. Up until now, there were no data available to indicate to what extent the human organism would react to such mix-and-match vaccination and start to form antibodies. A research team has now found that the antibody response is much stronger with the mix-and-match vaccine than with two doses of the AstraZeneca vaccine.

Researchers at Helmholtz Zentrum München, Technical University of Munich (TUM), Universitätsklinikum Erlangen and Universitätsklinikum Köln have now investigated this immune response within the framework of a retrospective scientific study. Blood samples were taken from 500 people who received a second vaccination with the mRNA vaccine from BioNTech/Pfizer nine weeks after their first AstraZeneca vaccine.

The result: The neutralizing antibody response was much higher in these people than in those who had received two doses of the AstraZeneca vaccine. The immune response to mix-and-match vaccines has proven to be just as good as the antibody response after two vaccinations with the mRNA vaccine from BioNTech/Pfizer. The study has now been published in the journal “The Lancet Infectious Diseases”.

Mix-and-match vaccines in case of intolerances or supply shortages

Based on the data they collected, the researchers have concluded that mix-and-match vaccines are a valid option. The mix is even more effective than two doses of the AstraZeneca vaccine, and might be used, for example, in individuals with allergies or if there are bottlenecks with supplies. The researchers also hope that the mix-and-match vaccine will be a further building block that can be used to improve the overall effectiveness of the Covid-19 vaccination. However, more studies are required to confirm the safety and clinical effectiveness of using this and other mix-and-match vaccines.

The study could be carried out so quickly thanks to assistance from several different parties: the Bavarian State Ministry of Science and the Arts as part of the CoVaKo-2021 project and the FOR-COVID consortium, the German Centre for Infection Research (DZIF) and the vaccination network VACCELERATE (funded by the EU programme Horizon 2020). The aim of CoVaKo-2021 and FOR-COVID is for scientists to monitor the introduction of Covid-19 vaccinations in Bavaria. The study was led by Ulrike Protzer (Munich), Klaus Überla (Erlangen) and Oliver Cornely (Cologne).

Bernd Sibler, Bavarian State Minister for Science and the Arts, emphasizes: “The results of this study have a direct impact on our vaccination strategy. They help us to use vaccinations as effectively as possible and act as an important basis for political decisions regarding our vaccination strategy in the future. The work of our scientists at the Faculty of Medicine and the university hospitals is indispensable for finding a way out of the Covid-19 pandemic.”

Original Publication:
Tenbusch et al., 2021: Heterologous prime-boost vaccination with ChAdOx1 nCoV-19 and BNT162b2. The Lancet Infectious Diseases, DOI: 10.1016/S1473-3099(21)00420-5