Mixture of Pfizer and AstraZeneca with Moderna gives better immune response

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A major British study of the Covid-19 vaccine mix found on Monday (6) that vaccinates achieved a better immune response when they received a first dose of AstraZeneca or Pfizer followed by one of Moderna after nine weeks .

“We found a very good immune response across the board, actually higher than the threshold set by the two doses of the Oxford/AstraZeneca vaccine,” Oxford University professor Matthew Snape in charge of Com-COV2 research told Reuters .

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The findings supporting dose blending will offer some hope to poor and middle-income countries, which may need to match different brands between the first and second dose if supplies run low or become unstable.

“I think the data from this study will be especially interesting and valuable for low- and middle-income countries, where they are still offering the first two doses of vaccines,” said Snape.

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“We’re showing that you don’t have to limit yourself to getting the same vaccine for a second dose, and that if the program is carried out more quickly using multiple vaccines, it’s okay to do that.”

If the AstraZeneca/Oxford vaccine is followed by a dose of Moderna or Novavax (which have not yet been regulated in Brazil), it produced more antibody and T-cell responses compared to two doses of AstraZeneca/Oxford, according to researchers at the University of Oxford.

The study of 1,070 volunteers also found that one dose of the Pfizer-BioNTech vaccine followed by one dose of Moderna was better than two doses of the standard Pfizer/BioNTech course.

Pfizer/BioNTech followed by Novavax induced antibodies higher than the Oxford/AstraZeneca two-dose schedule, although this schedule induced lower T-cell and antibody responses than the Pfizer/BioNTech two-dose schedule.

No vaccine safety concerns were raised, according to the study published in the medical journal Lancet.

Many countries have implemented vaccine interchangeability long before more effective data are available. As countries face rising numbers of infections, limited supplies and slow immunization due to some security concerns.

The longevity of protection offered by vaccines has been evaluated, with booster doses also being considered amid the increase in cases. New variants, including Delta and Omicron, have increased pressure to accelerate vaccination campaigns.

Participants’ blood samples were tested against the Wild-Type, Beta and Delta variants, according to the researchers in the Com-COV2 study, adding that the vaccines’ effectiveness against the variants declined, but this was consistent across mixed courses.

The deployment of vaccines using technology from different platforms – such as mRNA from Pfizer and Moderna, the viral vector from AstraZeneca and the protein-based injection from Novavax – and within the same timetable is new.

The results could 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 any of the other immunizers in the study generated a particularly robust response, consistent with the June results.

The study was defined as “non-inferiority” – the intention is to demonstrate that the mixture is not substantially worse than standard vaccine schedules – and compares immune system responses to the standard responses reported in previous clinical trials of each vaccine.

Reference: CNN Brasil

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