BRITAIN has three different Covid vaccines approved for use – and the country’s jab roll out is among the fastest in the world.
But with all requiring two doses for the full benefit, many have been left questioning the possibility of mixing jabs, so what do we know so far?
Can you mix Covid jabs?
The Pfizer/BioNTech vaccine was the first to get regulatory approval and to be rolled out in the UK on December 8, 2020.
The Oxford/AstraZeneca was given the green light on December 30, 2020, and GPs began administering jabs less than a week later.
Just three weeks after the UK’s vaccination programme got under way, experts changed the dosing regime changed from 3-4 weeks to 12 weeks.
It means many people who have already received the Pfizer jab have to wait a bit longer to get their second dose, while millions receive their first.
Mixing the two doses wasn’t something scientists initially tested in trials, so it’s currently unclear whether you can have one and then the other.
When will we know if they can be mixed?
The Government has announced a study is being launched to determine whether different vaccines can safely be used for the first and second doses.
The programme, which has received £7 million in funding from the Government’s Vaccine Taskforce, aims to establish whether a mixed-dose vaccine regimen is better than, or a good alternative to, using two doses of the same Covid-19 jab.
England’s deputy chief medical officer Professor Jonathan Van-Tam, who is the senior responsible officer for the new study, said that being able to mix vaccines would give greater flexibility in future.
“Given the inevitable challenges of immunising large numbers of the population against Covid-19 and potential global supply constraints, there are definite advantages to having data that could support a more flexible immunisation programme, if needed and if approved by the medicines regulator,” he said.
“It is also even possible that by combining vaccines, the immune response could be enhanced giving even higher antibody levels that last longer; unless this is evaluated in a clinical trial we just won’t know.”
The study, dubbed Com-Cov, will initially look at mixing doses of the Oxford University/AstraZeneca and Pfizer/BioNTech vaccines, as well as different intervals between doses.
But researchers at the National Immunisation Schedule Evaluation Consortium (NISEC), which is carrying out the study said more vaccines will be added to the list as they get approved for use.
Initial results expected to become available during the summer – in time to inform policy on the use of booster vaccines among younger age groups.
What’s the current vaccine mixing guidance?
Patients should receive the same type of Covid-19 vaccine for their first and second doses, Public Health England (PHE) has said.
However, if the same vaccine is not available or if there is no record of which vaccine the person had first, they could be given different brands.
Mary Ramsay, head of immunisations at PHE, told The BMJ: “Every effort should be made to give [patients] the same vaccine, but where this is not possible it is better to give a second dose of another vaccine than not at all.”
Covid-19 vaccines are currently being rolled out to priority groups including care home residents and staff, people over 80, and health and care workers.
In its Green Book,1 which provides guidance to healthcare professionals, PHE said that it was preferable for patients to get the same vaccine type but that it was “reasonable to offer one dose of the locally available product to complete the schedule.”
It added that this option was “preferred if the individual is likely to be at immediate high risk or is considered unlikely to attend again”.
The guidance continues: “In these circumstances, as both the vaccines are based on the spike protein, it is likely the second dose will help to boost the response to the first dose.”