Countries defend growing use of mix-and-match Covid-19 shots

Canadian officials and doctors have come out defending the mix and match approach to the administration of COVID-19 vaccines, just a day after the World Health Organization (WHO) cautioned about getting jabs from different makers.

“It’s a little bit of a dangerous trend here. We are in a data-free, evidence-free zone as far as mix and match,” said WHO’s Soumya Swaminathan on Monday in an online briefing.

He added that “it will be a chaotic situation in countries if citizens start deciding when and who will be taking a second, a third and a fourth dose.”

Dr Soumya said WHO has received “a lot of queries” about people who have received a first dose of a COVID-19 vaccine from one pharmaceutical company and were planning to take another shot from a different authorized drug maker.

Backing up Canada, Thailand has also defended mixing two different Covid-19 vaccines to battle a surge in infections.

Read also: Kenyan hospitals buckle as highly infectious Delta strain spreads

Authorities said they will mix a first dose of the Chinese-made Sinovac jab with a second dose of AstraZeneca to try and achieve a “booster” effect in six weeks instead of twelve.

Thailand’s chief virologist Yong Poovorawan said this would be possible by combining an inactivated virus vaccine, Sinovac with a viral vector vaccine such as AstraZeneca.

“We can’t wait 12 weeks (for a booster effect) in this outbreak where the disease is spreading fast,” he said.

“But in the future, if there are better, improved vaccines… we will find a better way to manage the situation, adding that “We are in a bit of a data-free, evidence-free zone as far as ‘mix-and-match.”

Thailand is currently struggling to contain its latest outbreak which is being fueled by the highly contagious Delta variant, with cases and deaths skyrocketing and the healthcare system stretching to the limits.

Further Spain and Germany are already offering the Pfizer or Moderna mRNA vaccines as a second dose to younger people who received a first dose of the AstraZeneca jab, following concerns about rare but serious blood clots, rather than about efficacy.

A UK study had found out that a mix-and-match approach to Covid vaccines using different brands for first and second doses appears to give good protection against the pandemic virus.

The trial results also hinted that people who had already received two doses of AstraZeneca vaccine could have a stronger immune response if they were given a different jab as a booster if recommended in the autumn.

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