Walgreens health workers throw up Pfizer BioNTec’s coronavirus disease (COVID-19) vaccine at the Victor Walchirk Apartments in Evanston, Illinois on February 22, 2021.

Kamil Krzaczynski | Reuters

LONDON – The mixing and matching of coronavirus vaccines from Pfizer-BioNTech and AstraZeneca-Oxford creates a “robust” immune response against the virus, according to a study led by Oxford University.

Researchers who conducted the Oxford-led Com-COV study, which looked at the feasibility of using a different vaccine for the first “primary” vaccination than the subsequent “booster” vaccine, found that alternating doses of the two vaccines caused a produced strong immunity.

However, the study found that immune responses differed depending on the sequence of vaccinations, with Oxford-AstraZeneca vaccination followed by Pfizer BioNTech vaccine producing the better immune response from the two mixed vaccination schedules.

The doses of the vaccines were given four weeks apart with dates for an upcoming 12-week dosing interval, the researchers said after posting their latest results on the Lancet Pre-Print server Monday.

“Both ‘mixed’ schemes (Pfizer-BioNTech followed by Oxford-AstraZeneca and Oxford-AstraZeneca followed by Pfizer-BioNTech) induced high levels of antibodies to the SARS-CoV2 spike IgG protein when the doses were four weeks apart were administered, ”the researchers noted.

“This means that all possible vaccination plans with the Oxford-AstraZeneca and Pfizer-BioNTech vaccines could potentially be used against Covid-19.”

The results could give much-needed flexibility to vaccination programs around the world, according to Matthew Snape, associate professor of pediatrics and vaccinology at Oxford University and lead investigator on the study.

“The Com-COV study evaluated ‘mix-and-match’ combinations of the Oxford and Pfizer vaccines to see the extent to which these vaccines could be used interchangeably, potentially allowing flexibility in the UK and the introduction of vaccines around the world . “

“The results show that both mixed regimens, when administered four weeks apart, induce an immune response in excess of the threshold set by the standard Oxford / AstraZeneca vaccine regimen.”

The researchers found that both mixed regimens induced higher levels of antibodies than the “standard” regimen with two doses of Oxford-AstraZeneca. It is currently recommended that the two doses required for the AstraZeneca vaccine be given eight to twelve weeks apart. Previous clinical studies found that the longer gap between doses increased the effectiveness of the AstraZeneca-Oxford vaccine against symptomatic Covid-19 infection to 82.4%.

The highest antibody response in the new study was observed on the Pfizer-BioNTech scheme with two doses, and the highest T-cell response was from an Oxford-AstraZeneca shot, followed by Pfizer-BioNTech, the researchers found, without further ado To give details.

The Covid vaccines currently approved in the UK and US stimulate our immune system to make antibodies to protect us from infection. Antibodies are produced by specialized white blood cells called B lymphocytes or B cells. T cells, on the other hand, are a second type of white blood cell that also play an important role in our immune system; T cells can attack cells that have been infected with a pathogen or virus such as Covid, and B cells can help produce antibodies.

“These results are an invaluable guide to using mixed dosing schedules, but the four week interval studied here is shorter than the eight to twelve week schedule most commonly used for the Oxford-AstraZeneca vaccine for improved immune response, and the results for one 12 week intervals will be available shortly, “added Snape.

The UK vaccination program has so far been praised for its speed and agility. The UK has approved and deployed vaccines quickly and is now offering all over 18s their first vaccinations while the rest of the people get their second dose. So far, 84.1% of UK adults have received a first dose and 61.6% two doses of a Covid vaccine, government data shows.

Given the UK’s easy access to Covid vaccines (it has ordered 397 million vaccine doses from six different vaccine developers), there are currently no plans to change the schedule of doses being offered to people, England’s Deputy Chief Medical Officer Professor Jonathan Van-Tam said in the Press release.

“Our unmixed (homologous) vaccination program has already saved tens of thousands of lives across the UK, but we now know that mixed doses could give us even more flexibility for a refresher program while supporting countries that need to go further and possibly further vaccine rollouts Have delivery problems, “he said.

In May, researchers reported preliminary Com-COV data showing more frequent mild to moderate reactions on mixed regimens compared to standard regimens, but these were short-lived.

Read more: Mix-and-match study with Covid vaccine shows an increased risk of mild to moderate symptoms

The University of Oxford is leading the Com-COV study conducted by the National Immunization Schedule Evaluation Consortium and backed by the Vaccines Task Force with £ 7 million ($ 9.7 million) in government funding.