First the vaccine from Astra Zeneca and then that from Biontech / Pfizer – or vice versa. Is it feasible to use a different vaccine for primary vaccination than for booster? If that were possible, it would make the whole vaccination program much more flexible.
Whether this is possible is now to be tested in Great Britain. Says Principal Investigator Matthew Snape, “If we show that these vaccines can be used interchangeably on the same schedule, it will not only greatly increase the flexibility of vaccine delivery, but it could also provide clues as to how the breadth of protection against new strains of the virus increases can be.”
Astra Zeneca and Biontech
The study is now recruiting more than 800 volunteers, ages 50 and older, from eight National Institute for Health Research (NIHR) -supported locations in England to examine the four different combinations of initial and booster vaccinations: A first dose of Oxford AstraZeneca vaccine, followed by a booster with either the Pfizer vaccine or another dose of the Oxford AstraZeneca vaccine, or a first dose of the Pfizer vaccine followed by a booster with either the Oxford AstraZeneca vaccine or another dose of the Pfizer vaccine.
These are examined in two different dosage regimens: at an interval of four weeks for an early interim evaluation and at a twelve-week interval.
Using blood samples drawn from the subjects, the study will monitor the effects of the various dosing regimens on participants’ immune responses and any additional side effects of the new vaccine combinations. The study will last 13 months.
Getting the best out of it
Maheshi Ramasamy, Senior Clinical Researcher and Investigator on the study, explains the details: “With the introduction of vaccination in the UK, we can look into how we can get the most out of the vaccines available to us. Now let’s look into using different combinations of two currently approved vaccines is a good alternative to the standard vaccination schedule. We will also examine the effect of the interval between doses on immune responses. “
Boost immune response?
According to the principal investigator, Professor Jonathan Van-Tam: “Given the inevitable challenges of immunizing large numbers of people and possible global supply shortages, it is beneficial to have data that could support a more flexible immunization program, if required and approved by the Medicines Agency. “
It is even possible that the combination of vaccines could strengthen the immune reaction, which could lead to even higher and longer-lasting antibody levels: “We will only know that when we have the data.”