ÐÇ¿Õ´«Ã½

Skip to main content

Mix-and-match approach boosts immune response of AstraZeneca shot, study finds

Share
LONDON -

A mixed schedule of vaccines where a shot of Pfizer's COVID-19 vaccine is given four weeks after an AstraZeneca shot will produce better immune responses than giving another dose of AstraZeneca, an Oxford study said on Monday.

, called Com-COV, compared mixed two-dose schedules of Pfizer and AstraZeneca vaccines, and found that in any combination, they produced high concentrations of antibodies against the coronavirus spike protein.

The data provides support for the decision of some European countries that have started offering alternatives to AstraZeneca as a second shot after the vaccine was linked to rare blood clots.

Matthew Snape, the Oxford professor behind the trial, said that the findings could be used to give flexibility to vaccine rollouts, but was not large enough to recommend a broader shift away from clinically approved schedules on its own.

"It's certainly encouraging that these antibody and T-cell responses look good with the mixed schedules," he told reporters.

"But I think your default has to stay, unless there's a very good reason otherwise, to what is proven to work," he added referring to the same-shot vaccine schedules assessed in clinical trials.

The highest antibody response was seen in people receiving two doses of Pfizer vaccine, with both mixed schedules producing better responses than two doses of AstraZeneca vaccine.

An AstraZeneca shot followed by Pfizer produced the best T-cell responses, and also a higher antibody response than Pfizer followed by AstraZeneca.

The results were for combinations of vaccines given at four-week intervals to 830 participants.

Com-COV is also looking at mixed schedules over a 12-week interval, and Snape noted that AstraZeneca's shot was known to produce a better immune response with a longer interval between doses.

In Britain, officials have suggested an eight-week gap between vaccine doses for over-40s and a 12-week gap for other adults.

"Given the UK’s stable supply position there is no reason to change vaccine schedules at this moment in time," England's Deputy Chief Medical Officer Jonathan Van-Tam said, adding that the data on a 12-week interval would influence future decisions on the rollout program.

Over 80% of adults in Britain have now received one dose of COVID-19 vaccine and 60% have had two shots.

CTVNews.ca ÐÇ¿Õ´«Ã½

The province's public security minister said he was "shocked" Thursday amid reports that a body believed to be that of a 14-year-old boy was found this week near a Hells Angels hideout near Quebec City.

Local Spotlight

They say a dog is a man’s best friend. In the case of Darren Cropper, from Bonfield, Ont., his three-year-old Siberian husky and golden retriever mix named Bear literally saved his life.

Paleontologists from the Royal B.C. Museum have uncovered "a trove of extraordinary fossils" high in the mountains of northern B.C., the museum announced Thursday.

The search for a missing ancient 28-year-old chocolate donkey ended with a tragic discovery Wednesday.

The Royal Canadian Mounted Police is celebrating an important milestone in the organization's history: 50 years since the first women joined the force.

It's been a whirlwind of joyful events for a northern Ontario couple who just welcomed a baby into their family and won the $70 million Lotto Max jackpot last month.

A Good Samaritan in New Brunswick has replaced a man's stolen bottle cart so he can continue to collect cans and bottles in his Moncton neighbourhood.

David Krumholtz, known for roles like Bernard the Elf in The Santa Clause and physicist Isidor Rabi in Oppenheimer, has spent the latter part of his summer filming horror flick Altar in Winnipeg. He says Winnipeg is the most movie-savvy town he's ever been in.

Edmontonians can count themselves lucky to ever see one tiger salamander, let alone the thousands one local woman says recently descended on her childhood home.

A daytrip to the backcountry turned into a frightening experience for a Vancouver couple this weekend.

Stay Connected