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December 6 (Reuters) – A large UK study of mix of COVID-19 vaccines has found that people had a better immune response when they received a first dose of AstraZeneca or Pfizer-BioNTech shots followed by Moderna nine weeks later , according to the results on Monday.
“We found a really good immune response across the board … actually higher than the threshold set by the Oxford-AstraZeneca vaccine two doses,” Matthew Snape, the Oxford professor behind the experiment called Com-COV2, told Reuters.
The results, which support flexible dosing, will give hope to poor and middle-income countries, which may have to combine different brands between first and second shots if supplies run out or become unstable.
“I think the data from this study will be particularly interesting and valuable for low- and middle-income countries, where they are still rolling out the first two doses of vaccines,” Snape said.
“We show … you do not have to hold on to receiving the same vaccine for a different dose … and that if the program will be delivered faster by using more vaccines, then it’s okay to do so.”
If the AstraZeneca-Oxford (AZN.L) vaccine is followed by a Moderna (MRNA.O) or Novavax (NVAX.O) shot, according to researchers, higher antibodies and T-cell responses were induced compared to two doses of AstraZeneca-Oxford. at the University of Oxford.
The study of 1,070 volunteers also found that a dose of the Pfizer-BioNTech (PFE.N), (22UAy.DE) vaccine followed by a Moderna (MRNA.O) shot was better than two doses of the standard Pfizer-BioNTech course.
Pfizer-BioNTech followed by Novavax induced antibodies higher than the 2-dose Oxford-AstraZeneca regimen, although this regimen induced lower antibody and T-cell responses than the 2-dose Pfizer-BioNTech regimen.
No safety concerns were raised, according to the Oxford University study published in the medical journal Lancet.
Many countries have implemented a mix and match long before robust data was available, as nations faced sky-high infection rates, low supplies and slow immunization due to some security issues.
The duration of the protection offered by vaccines has been studied and booster doses have also been considered in the midst of increasing cases. New variants, including Delta and Omicron, have now increased the pressure to speed up vaccination campaigns.
Blood samples from participants were tested against the Wild-Type, Beta and Delta variants, said researchers from the Com-COV2 study, adding that the efficacy of the vaccines against the variants had decreased, but this was consistent across mixed courses.
Implementing vaccines using technologies from different platforms – such as Pfizer and Modernas mRNA, AstraZeneca’s viral vector and Novavax’s protein-based shot – and within the same schedule is new.
The results may inform new approaches to immunization against other diseases, he said.
The study also found that a first dose of the AstraZeneca-Oxford vaccine, followed by one of the other candidates in the study, generated a particularly robust response, consistent with the results in June.
The study was designed as a so-called “non-inferiority” study – the intention is to demonstrate that mixing is not significantly worse than the standard schemes – and compares the immune system’s responses with the gold standard responses reported in previous clinical trials with each vaccine.
Reporting of Pushkala Aripaka in Bengaluru; Edited by Josephine Mason and Mark Heinrich
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