Landmark study on mixing vaccine doses launches in Newcastle

A new UK study investigating whether different coronavirus vaccines can be mixed to improve protection is taking place in Newcastle.

The Com-Cov study, which started alternating doses of the Oxford/AstraZeneca and Pfizer vaccines, will now include the Moderna and Novavax vaccines.

Adults over the age of 50 who have received their first vaccination in the past 8 to 12 weeks will be recruited to take part in the research, which will be run at the Newcastle Freeman hospital.

Led by the University of Oxford, the study will be run by the National Immunisation Schedule Evaluation Consortium (NISEC) across nine National Institute for Health Research (NIHR) supported sites.

It is backed through funding from the Vaccines Taskforce and the Coalition for Epidemic Preparedness Innovations.

Study participants, who have already received either the Oxford-AstraZeneca or Pfizer vaccine, will be randomly allocated to receive either the same vaccine for their second dose, or a dose of the vaccines produced by Moderna or Novavax.

Working across nine sites in the UK, the researchers will study reactogenicity (any adverse reactions) and the immune system responses to these new combinations of vaccines.

The study is designed as a so-called ‘non-inferiority’ study and will compare the immune system responses to the gold-standard responses reported in previous clinical trials of each vaccine.

If the study shows promising results, the regulators MHRA and JCVI would formally assess the safety and efficacy of any new vaccination regimen before it would be rolled out to patients.

Matthew Snape, associate professor in paediatrics and vaccinology at the University of Oxford, and chief investigator on the trial, said: “The focus of both this and the original COM-COV study is to explore whether the multiple COVID-19 vaccines that are available can be used more flexibly, with different vaccines being used for the first and second dose.

“If we can show that these mixed schedules generate an immune response that is as good as the standard schedules, and without a significant increase in the vaccine reactions, this will potentially allow more people to complete their COVID-19 immunisation course more rapidly.

“This would also create resilience within the system in the event of a shortfall in availability of any of the vaccines in use.”

Dr Chris Duncan, principal investigator of the study in Newcastle, added: “Clinical studies into COVID-19 vaccines remain critical to help find several safe and effective candidates to help protect us all.

“Studies such as Com-Cov2 can help us learn more about the flexibility of COVID-19 vaccine schedules.”