Mixing Covid vaccines generates robust immune response, study finds

No safety concerns were raised in this study of 1,070 participants. Credit: PA

First doses of the Oxford/AstraZeneca or Pfizer/BioNTech coronavirus vaccines followed by second doses of the Moderna or Novavax jabs will generate stronger immune responses against Covid-19, researchers have found.

According to the study, participants who received a first dose of the Oxford or Pfizer jab generated a robust immune response when given a second dose of vaccines manufactured by Novavax or Moderna nine weeks later.

No safety concerns were raised in this study of 1,070 participants, the University of Oxford-led Com-COV study found.

Listen to our coronavirus podcast:

Researchers say the study supports the flexible use of these vaccines in primary immunisation schedules, which is crucial to help their rapid deployment especially in low-and middle-income countries where vaccine supply may be inconsistent.

Matthew Snape, associate professor in paediatrics and vaccinology at the University of Oxford, and chief investigator on the trial, said: “Thanks to studies such as these, we are now getting a more complete picture of how different Covid-19 vaccines can be used together in the same vaccine schedule.

“Encouragingly, all these schedules generated antibody concentrations above that of the licensed and effective two-dose Oxford/AstraZeneca schedule.

“When it comes to cellular immunity, having a first dose of the Oxford/AstraZeneca vaccine followed by any of the other study vaccines generates a particularly robust response”.

The research found that both Oxford followed by Moderna/Novavax schedules both induced higher antibodies and T-cell responses than the licensed and highly effective standard two-dose Oxford schedule.

Pfizer/Moderna induced higher antibody and T-cell responses than the standard two-dose Pfizer schedule.

And Pfizer/Novavax induced higher antibodies than the two-dose Oxford schedule which induced lower antibody and T-cell responses than the two Pfizer doses.

Researchers also looked at the vaccine responses to different coronavirus variants.

A covid vaccination centre Credit: ITV News

Blood samples taken from participants were tested for their effectiveness against the Wild-Type, Beta and Delta variants.

While it was observed that the vaccines’ efficacy against the variant strains had decreased, this was a consistent trend across the mixed schedules.

The study, published in The Lancet, also found that a significantly higher number of short-lived vaccine reactions were reported in volunteers who received a second dose of Moderna compared to those who received two doses of the Oxford or Pfizer jabs.