A UK trial looking at whether different Covid-19 vaccines can be safely mixed needs volunteers.
So who can take part?
The scientist leading the trial is looking for people aged 50 and over to take part in the government-backed study to determine whether different coronavirus vaccines can safely be used for the first and second doses.
Currently, people receive one dose of either the Pfizer/BioNTech or Oxford/AstraZeneca vaccine and then their second dose 12 weeks later.
How can I take part?
You can take part if you're on the NHS COVID-19 Vaccine Research Registry. You can volunteer to be contacted about taking part in the study and further vaccine studies by joining the registry.
What will I have to do?
Patients taking part will receive different Covid-19 vaccines for each dose. Vaccinations are expected to start towards the middle of the month and the study will last for 13 months.
You can sign up online. You'll be asked some questions about yourself, and then for permission for the researchers to contact you.
What will this study show us?
The programme aims to establish whether a mixed-dose vaccine regimen is better than, or a good alternative to, using two doses of the same coronavirus jab.
How will it be rolled out?
Some will receive the Oxford-AstraZeneca jab followed by the Pfizer-BioNTech vaccine or vice versa - four or 12 weeks apart. More vaccines will be added to the list as they get approved for use in the UK.
When can we expect results?
Initial results are expected to become available during the summer – in time to inform policy on the use of booster vaccines among younger age groups.
Will this trial change anything about the current roll out?
There are no current plans for any changes. People will continue to get two of the same type of vaccine, 12 weeks apart.
Speaking on Sky News, Chief investigator in the Com-Cov study, Professor Matthew Snape said those with underlying health conditions such as diabetes or heart disease will be able to take part in the trial because "we are trying to get a population that is representative of the UK".
He said the study will look at whether mixing doses of the Oxford University/AstraZeneca and Pfizer/BioNTech vaccines is as good as using two doses of the same Covid-19 jab.
"We are looking to see if the immune response that generates is as good as the currently approved schedules," he added.
Vaccines minister Nadhim Zahawi said: "The UK remains at the forefront of Covid vaccine and, of course, research overall. This (study) is looking at how we can develop, be even more efficient for the UK, but also the rest of the world."
He stressed that it would not impact the current deployment of jabs.
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