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St George’s trial leads to first Omicron vaccine approval

Published: 15 September 2022

The UK has become the first country to approve an Omicron variant Covid-19 vaccine. St George’s Vaccine Institute contributed important data for the approval and is conducting the pivotal phase 2 clinical trial.

The Vaccine Institute at St George’s, University of London and St George’s Hospital is the lead site for the Moderna Phase 2 trial, which compared the effectiveness of booster doses of Moderna’s new Omicron vaccine with its existing Spikevax vaccine. Both vaccines are based on mRNA, which the body uses as the instructions to create virus proteins for the immune system to recognise.

More than 2800 people over 16 years old across 26 sites nationwide participated in the trial, which was supported by the Vaccine Taskforce of the National Institute of Health Research (NIHR). In the first stage of the trial, participants were given their first or second booster of either the new variant vaccine or SpikeVax, Moderna’s licenced vaccine. The second stage of the trial saw people given a 50:50 mixture of the two vaccines or standard Spikevax.

It is this 50:50 mixture which will become part of the UK’s autumn booster campaign, which is in its early stages across the country.

Results have shown that people given the new vaccine produced higher levels of antibodies to Omicron variants than those given the original Spikevax vaccine, while having a similar safety profile. The trial is ongoing and will continue to follow up participants to monitor the extent to which the vaccine protects them from infection or severe disease.

“What’s interesting is that the dual-strain vaccine seems to stimulate a better immune response than either of the vaccines alone,” said Dr Catherine Cosgrove, Chief Investigator of the trial and Adult Lead at the Vaccine Institute.

“We’re not sure why, but it could be because the new variant vaccine is arriving along with a vaccine that your body has encountered before, so the immune response is heightened.”

“Being an infectious disease consultant and having seen the impact of Covid-19 on patients first-hand, it’s been amazing working on these trials,” added Dr Cosgrove. 

“We’re really pleased to have contributed to this approval in time for the autumn booster campaign, and we’re so grateful to the people who are so willing to come forward and help with clinical trials.”

- Dr Catherine Cosgrove -

“It’s also a testament to just how well set up we are for clinical trials in the UK. We’ve got a great network of organisations, spearheaded and supported by NIHR, which I hope will continue beyond Covid-19. The smooth collaboration between St George’s, University of London and St George’s Hospital is also great for patients and volunteers, now and in the future.”

The Moderna dual-strain vaccine was approved by the Medicines and Healthcare products Regulatory Agency (MHRA) on 15 August. A second vaccine from Pfizer/BioNTech has since been approved.

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