According to The New York Times, the mixing and matching doses could help countries weather vaccine supply shortages.
The Com-Cov (Comparing Covid-19 Vaccine Schedule Combinations) study led by the University of Oxford began in February using AstraZeneca and Pfizer shots, but on Wednesday the researchers announced that they would recruit more volunteers and expand the trial to include doses of the vaccines developed by Novavax and Moderna.
Matthew Snape, Associate Professor in Paediatrics and Vaccinology at the University of Oxford, and Chief Investigator on the trial said in a statement: “The focus of both this (known as COM-COV 2) 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,” he added.
Researchers are expecting to publish their first findings by July, although the study will run for a year.
According to the official statement, the additional study will seek to recruit adults aged over 50 who have received their first, or ‘prime’ vaccination in the past 8-12 weeks.
These volunteers, who will have 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 Covid-19 vaccines produced by Moderna or Novavax.
The six new ‘arms’ of the trial will each recruit 175 candidates, adding a further 1050 recruits into this programme.
Snape continued: “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.”
Some governments have also recommended that some people who have received a first dose of the AstraZeneca vaccine receive a second injection of a different vaccine after a small number of recipients developed a rare blood-clotting disorder, as reported by NYT.
Led by the University of Oxford, run across nine National Institute for Health Research supported sites by the National Immunisation Schedule Evaluation Consortium, and backed through funding from the Vaccines Taskforce and the Coalition for Epidemic Preparedness Innovations, the additional study will seek to recruit adults aged over 50 who have received their first, or ‘prime’ vaccination in the past 8-12 weeks.
According to Sputnik, the Moderna vaccine was recently added to the UK’s immunization program, which has already seen over 32,2 million people given at least one dose of a Covid-19 vaccine, while the Novavax drug is still waiting for the green light from the UK regulator.