“Mixing and matching is not uncommon,” said Angela Rasmussen, a virologist at Saskatoon Vaccines and Infectious Diseases.

“I think it does create a more flexible situation, which is very good overall because we don’t need to think about vaccinating everyone in Canada only — we need to think about vaccinating everyone in the world.”

Given the delay in supply and safety issues associated with certain other vaccines, more and more countries are considering including different COVID-19 vaccines as second or booster doses into their plans.

Watch | What we know about the hybrid COVID-19 vaccine:

Bahrain, Bhutan, Indonesia, Italy, Thailand, the United Arab Emirates, Uruguay and Vietnam are exploring or actively pursuing mixed drug delivery strategies.

According to Rasmussen and other vaccine experts, this initiative is increasingly supported by new research, even though it is rooted in decades of vaccine science.

“Combined vaccines are nothing new,” she said. “There is no reason to expect it to be insecure.”

“It has been accepted by other vaccines worldwide,” she said. “You ask what flu vaccines you get every year? They are made by different manufacturers.”

For some countries, including Italy and Vietnam, the goal is to provide a second dose of mRNA products, such as Pfizer-BioNTech, to people who have received the AstraZeneca-Oxford vaccine for the first time.

Watch | Passengers receiving mixed vaccines stated that they could not board certain cruise ships:

Many Canadians who have received mixed doses of the COVID-19 vaccine face travel problems in countries that do not recognize that they are fully vaccinated. Travel bloggers Karen and Brian Hosier shared how “frustrating” rules affect their travel plans and business. 6:34

This is similar to the guidelines of the National Advisory Committee on Immunization of Canada (NACI), which allows the replacement of different doses of different vaccines in some cases.

The advisory body suggested that AstraZeneca or an mRNA-based vaccine—Moderna is another vaccine approved in Canada—can be provided as a second dose to people who are given AstraZeneca for the first time.

But the team pointed out that due to emerging safety evidence and the possibility of a better immune response, the mRNA option is preferred as the second dose.

The combined dose of Pfizer and AstraZeneca vaccine actually produces a stronger immune response than two rounds of AstraZeneca. Based on a British study published in June that has not yet been peer-reviewed.

recent, As originally reported by ReutersA similar study of nearly 500 medical workers in South Korea also showed that compared with two doses of AstraZeneca, this method—first AstraZeneca and then Pfizer booster—increased the level of neutralizing antibodies by six. Times.

Canada’s NACI also called for the same mRNA vaccine to be used for the second dose if possible, but stated that if the first vaccine is not available, another mRNA vaccine “can be considered interchangeable”.

“Accept” method

Dr. Alexander Huang, an infectious disease expert at the University of Saskatchewan, said there is “a certain degree of pragmatism” when it comes to the increasing use of mixed vaccines around the world.

He said that not every country has “excellent access” to mRNA injections, which is “really the bottom line.”

Some countries, such as Thailand and the United Arab Emirates, allow Pfizer injections to be used as a booster for people who are vaccinated for the first time with one of China’s leading vaccines produced by China Industrial and Sinopharm – although there is no study on whether this will improve people’s protection. Level.

“We just need some harder and faster clinical data,” he said.

Wong also said that there are still controversies about mixing different brands and technologies around the world.

Although some countries use a mixed dosing regimen, in other countries, if certain vaccines are mixed, it will directly prevent people from entering the country-this is a Some cruise companies are in a similar situation And overseas tourist attractions.