Alternating vaccines trial to include two additional vaccines

Note: If you've come to this page because you've heard of this clinical trial and would like to enquire about taking part, please visit the study website.

The Com-Cov trial looking at alternating vaccines has been expanded to include two additional vaccines. The trial, launched in February at UCLH and other UK sites to investigate alternating doses of the Oxford-AztraZeneca and Pfizer vaccines, will now include the Moderna and Novavax vaccines in a new study.

The additional study will be recruiting adults aged over 50 who have received their first vaccination in the past 8-12 weeks. The study, designated as an Urgent Public Health study by the NIHR, is led overall by the University of Oxford, run by the National Immunisation Schedule Evaluation Consortium (NISEC), funded by the Vaccines Task Force and the Coalition for Epidemic Preparedness Innovations.

Researchers plan to recruit a total of 1,050 participants across eight UK sites in this additional study. Up to 180 participants will take part at UCLH, which was the first site to vaccinate volunteers in the first portion of the Com-Cov trial.

Volunteers, who will have received either the Oxford-AstraZeneca or Pfizer vaccine as their first dose, will be randomly allocated to receive either the same vaccine for their second dose, or a dose of the Covid-19 vaccines produced by Moderna or Novavax.

The researchers will study adverse reactions (reactogenicity) and immune system responses to  vaccine combinations. 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.

Professor Vincenzo Libri, Director of the NIHR UCLH Clinical Research Facility and the UCLH Vaccine Research Centre, who is Principal Investigator of the ComCov trial at UCLH, said: “As in the first part of the trial, we hope to be able to show that combining vaccines can generate an immune response that is as good and as safe as using the same vaccine for both doses. This would give us flexibility in terms of the vaccine roll out.

“We were delighted to complete recruitment to the first part of the ComCov study at UCLH very rapidly – and we encourage people from across our local communities to register their interest in taking part.”

Matthew Snape, Associate Professor in Paediatrics and Vaccinology at the University of Oxford, and Chief Investigator on the trial said:

“We saw a fantastic response to the public from the original Com-Cov study, with 830 participants recruited over eight sites in a two-week period in February. We look forward to working with this network and several new sites for the Com-Cov2 study.”

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