Covid-19: ‘Mix-and-match’ booster welcomed

The decision to introduce mRNA booster shots has been welcomed by leading infectious disease experts, who say the ‘mix-and-match’ strategy will lead to stronger levels of protection.

Epidemiologist Emma McBryde says it is clear that combining vaccines is ‘better in the long run’ for Australia’s booster program. Picture: AFP

A federal government decision to introduce mRNA booster shots has been welcomed by leading infectious disease experts, who say the “mix-and-match” strategy will provide stronger levels of protection and fortify immunity across the population.

Since July, evidence has continued to mount in support of the “mix-and-match” strategy, after an Oxford University study revealed that one dose of AstraZeneca ­followed by a dose of Pfizer ­resulted in a stronger immune response than two doses of ­AstraZeneca.

A similar study, undertaken by German researchers, observed that an initial AstraZeneca shot followed by Pfizer generated a high number of protective antibodies.

On Wednesday, Health Minister Greg Hunt said Australia was monitoring booster programs across several countries – including Israel where the booster rollout is most advanced – which confirms the strategy is safe and effective across all age groups in decreasing infection and the possibility of severe disease.

James Cook University epidemiologist Emma McBryde said it was clear that combining vaccines was “better in the long run”, with two doses of AstraZeneca followed by a Pfizer vaccine “a good idea both for herd immunity and for direct effect”.

According to Professor McBryde, studies already indicated that having a Pfizer shot followed by an AstraZeneca shot was not effective, noting that a third AstraZeneca could potentially risk the development of auto-antibodies.

Australia will mostly use the Pfizer vaccine for boosters, after the government purchased an additional 85 million in July. The Moderna vaccine will also be used for boosters, and possibly the Novavax shot.

Health authorities have been careful to draw a distinction between “booster shots” for the general population and “third doses” for severely immunocompromised individuals.