Recruitment has begun in the UK for a worldwide study to examine whether using different COVID-19 vaccines for the first and second dose is as effective as using the same type of vaccine for all parts.
If successful, the practice of using intermittent doses would improve flexibility for mass vaccination and protect it from disruption in vaccine supply, scientists behind the study said.
They also raised the possibility that a primary stimulant heterologous vaccination regimen may provide even better protection against COVID-19 than using the same vaccine for two doses.
The study will run for more than a year
Work began today on recruiting 820 participants to participate in the 13-month randomized controlled study, run by the National Vaccination Register Assessment Consortium.
The COVID-19 Heterologous Prime Boost (Com-Cov) trial will initially focus on the two vaccines currently in use in the community: Pfizer / BioNTech and AstraZeneca / Oxford.
It will also collect immunological evidence at different intervals (28 days v 12 weeks) between the first and second dose for a mixed vaccine schedule against control groups where the same vaccine is used for both doses.
The trial, which will be held at eight different sites in England, will test eight different combinations. They are:
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Two doses of the AstraZeneca / Oxford vaccine at 28 days apart
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Two doses of the AstraZeneca / Oxford vaccine at 12 weeks apart – as a control group
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Two doses of the Pfizer / BioNTech vaccine at 28 days apart
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Two doses of the Pfizer / BioNTech vaccine at 12 weeks apart – as a control group
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AstraZeneca / Oxford vaccine for the first dose, followed by the Pfizer / BioNTech vaccine for the second dose, at 28 consecutive days
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AstraZeneca / Oxford vaccine for the first dose, followed by the Pfizer / BioNTech vaccine for the second dose, at 12 weeks apart
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Pfizer / BioNTech vaccine for first dose, followed by AstraZeneca / Oxford vaccine for second, at 28 days apart
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Pfizer / BioNTech vaccine for first dose, followed by AstraZeneca / Oxford vaccine for second, at 12 weeks apart
“We are starting with these two vaccine candidates, but the intention is to add additional vaccine candidates as long as they are available for regular use,” said Professor Matthew Snape of Group Oxford Vaccine, who is chief investigator of the case.
Blood samples are taken from participants over time to measure antibody levels.
Research will inform future vaccination programs
Dr Mary Ramsay, head of vaccination at Public Health England, said it was important to establish a “proof of principle” that a heterologous vaccine regimen would be a key stimulant effective in protecting people from COVID-19.
She told a briefing issued by the Science Media Center: “If they work well together, and may work better than both vaccines, then that will be very helpful, both for the UK and around the world, in terms of how we can implement programs, how we can make the programs as accessible as possible. “
Professor Jonathan Van-Tam, England’s deputy chief medical officer, said: “With the inevitable challenges of vaccinating large populations against COVID-19 and global supply constraints potentially, there are definite benefits in obtaining data that could support a more flexible vaccine. program, if required and approved by the pharmacist regulator.
“It is possible that even by combining vaccines, the immune response may be enhanced, producing even higher antibody levels that last longer.
If this is not assessed in a clinical trial we will not know. “
Dr Snape said there was emerging evidence that the timing of the vaccine mix could provide better protection. “You will see a better response with a combination of RNA and viral vectored responses,” he told the meeting.
When asked if the researchers were concerned about the safety of mixing and matching different vaccines, Dr Snape said: “We do not expect this to significantly increase the risk of relapse. -expecting side effects or side effects, but we look carefully for that. “
Government funding
Audit collectors will be selected from the NHS COVID-19 Vaccine Register. “We want to recruit people over 50, and people with comorbidities, and people from different backgrounds,” said Dr Maheshi Ramasamy, a consultant physician and senior clinical researcher at Oxford Vaccination Group.
The study was classified as an emergency Public Health study and received £ 7 million in Government funding through the Vaccines Task Force.
Nadhim Zahawi, minister for the use of COVID-19 vaccines, said: “This is a very important clinical trial that will provide more vital evidence of the safety of these vaccines when used in different ways.
“Nothing will be agreed for wider use than the study, or as part of our vaccine use program, so that researchers and the regulator can be fully confident that the approach is safe and effective.”
Interim results from COM-COV are expected in the summer.
Commenting on the study, Dr Andrew Garrett, executive vice president of scientific activity at ICON Clinical Research, said: “Many questions remain unanswered, and new questions will emerge, so it is important for the UK to develop an experimental framework. created to continue gather objective vaccine evidence to support public health policy.
“This test represents an important step in the right direction.”
Dr Peter English, a consultant in infectious disease control, welcomed the study into routine and longer doses. He said: “It appears that the short incubation period in the initial vaccine trials was chosen because the efficacy of a vaccine after a single dose was not expected to be as high as it was intended, to improve initial immunity. provided, at the expense of long-term immunity.
“So that the test looks at different interesting times and should provide some valuable data.”