Can we mix and match vaccines? A big question for two COVID-19 doses


TORONTO – If your first vaccine shot was made by a company, can you get a different vaccine for your second shot?

Scientists are looking to answer this question for the first time, and a new study out of the United Kingdom may soon be able to provide some guidance.

The concept has been dubbed the ‘mix and match’ – using different combinations of COVID-19 vaccines approved for the first and second doses within the same individual.

Questions about vaccine supply, as well as concerns related to specific vaccines, have placed some urgency behind the discovery of whether it works.

“You won’t be able to control the supply in the first and second doses, perhaps, as some other countries,” said Matthew Snape, a professor at the University of Oxford and the UK’s principal investigator of the study. “So these mixed schedules may well be the key to getting two doses in as many people in the world as possible.”

Led by the Oxford Vaccine Group, the COM-COV study was launched in February, and the results of the first phase – which included more than 800 volunteers aged 50 and over – are expected to be released in a few weeks.

It should be safe to take doses of various vaccines, experts say, so the most important question is whether this vaccine still works in combination.

But this is more than just adding vaccines for the purpose of increasing supply.

A UK study can also determine if two different shots give better results than one brand alone.

Some test subjects are receiving a single dose of AstraZeneca, which uses a cold virus to build immunity, and a shot of Pfizer, which infects the immune system with messenger RNA.

When researchers expanded the study in April, they added Modern and Novax to the vaccine that volunteers could receive.

Volunteers randomly received vaccines, with some receiving the same vaccine in their first and second doses to serve as a control group to determine if mixing vaccines produced a different immune response.

Previous studies with animals suggest that the use of a combination of vaccines produces durable antibodies against coronavirus infection, experts say.

“We also know from immunology experiments in animal models that sometimes mixing and matching vaccines gives you better protection, because each vaccine has its own characteristics,” Tania Watts, a professor of immunology at the University of Toronto, told CTV News told.

Based on the results of a UK study, a ‘mix and match’ strategy may present a new option for those who have received Astra Zeneca for their first dose and are now undergoing a short supply or rare blood clotting side effects. Are worried about.

The majority of AstraZeneca is manufactured in India, which is currently hard-hit by the virus, causing concern in provinces like BC, where tens of thousands received AstraZeneca as their first dose, that the second dose is not within Will arrive. Four month waiting period recommended by NACI.

“I’m really hoping by the end of this month that we can start seeing some data from Oxford [we] Can make an informed decision on that, ”said Vats.

We are in an “unprecedented” situation with the epidemic, Watts pointed out, and it is prompting us to ask new questions.

“We need to do everything to give the best response,” he said, adding that this research could “inform vaccine rollout on other diseases for years to come.”

The UK is not the only place to examine this concept. ‘Mix and match’ is already happening in Quebec in Canada, solely as a strategy to increase the number of people vaccinated.

In April, Quebec announced that it would replace the Pfizer vaccine for some long-term care residents who have modernized vaccines on the face of variants to vaccinate residents more quickly and to supply scarcity Gave her first shot.

Due to both mRNA vaccines, Pfizer and Modern are more similar than some other vaccines.

Dr., the lead physician for 15 long-term care facilities in Montreal. Sophie Zhang said that she did not set the dosage to mix, but responded to the supply shortage.

“The arrival of Modern’s shipment was delayed, and we decided that it was necessary to give them a second dose, and that we were ready to give them another type of vaccine sooner rather than wait for Modern.” Supplies to come, ”she said.

He said that he included about a few hundred people in mixed doses working in about half the households.

“I think in an ideal world what we would do when there is no scarcity, and there is no emergency, and then there is what we will do when there is a crisis,” Zhang said.

She said that they are watching closely for adverse reactions, but have seen nothing out of the ordinary.

“In terms of security, I think so far we have no worries and no worries,” she said. “Perhaps in the future it will also be something that will be recommended due to the fact that it can also boost the immune response.”

And CTV News has learned that Canada is about to begin its comprehensive ‘Mix and Match’ vaccine study.

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