Aussies given AstraZeneca should get Pfizer as their second jab

One way to overcome vaccine hesitancy could be to promise Pfizer as a second jab to people who get AstraZeneca.

The man who ran the federal government’s chief vaccine advisory body for a decade said he would have had a dose each of the AstraZeneca then Pfizer vaccines if the option was available.

Once there is enough supply of the Pfizer and Moderna vaccines, the federal government should give Australians who have had one dose of AstraZeneca the opportunity to get Pfizer as their second dose, Professor Terry Nolan — who was the head of the Australian Technical Advisory Group on Immunisations (ATAGI) from 2005 to 2014 — said.

“I’ve had two doses of AstraZeneca. If I had the choice I would have had AstraZeneca first and then Pfizer second because I think, very, very likely that’s going to turn out to be a much better immune protection both against the variants and also for protection against waning of immunity over time,” the vaccine expert from University of Melbourne, the Doherty Institute and the Murdoch Children’s Research Institute said.

“For me it’s a small dunk.”

Professer Terry Nolan.

Four key international studies have shown mixing the vaccine doses triggers an immune response similar to – or even better – than getting two doses of the Pfizer vaccine.

Further studies are needed to prove whether that translates into better protection.

“It should. And there’s no reason to think it wouldn’t, but that hasn’t been demonstrated because no one’s implemented this long enough and evaluated it yet,” Professor Nolan said.

Countries including Canada, Finland, France and Germany are already allowing mixed vaccine doses.

The stronger response came because “you’re stimulating the immune system through a different pathway”, he said.

Allowing Australians to mix and match Covid vaccines would not only strengthen immunity, it might help overcome some people’s reluctance to get the AstraZeneca shot.

While fear of extremely rare blood clots is the main reason Australians are shunning the AstraZeneca vaccine, others are doing so because they wrongly believe it is not as effective as Pfizer.

Allowing people to get AstraZeneca now, when it is the only vaccine in high supply, while letting them have Pfizer as a second dose in coming weeks, when it will be arriving in greater numbers, could help boost vaccination rates in the midst of the latest outbreak.

The trade-off is 30-40 per cent of people will have a side effect that might cause them to take time off work after each vaccine, whereas having the same jab twice usually produces just one side-effect experience.

The government’s expert advisory body the Therapeutic Goods Administration TGA) has so far only approved the vaccines for use if you get two doses of the same brand.

ATAGI has considered allowing the vaccines to be mixed but to date it has not made a ruling that would allow this.

The CSIRO’s head of biosecurity Dr Rob Grenfell said the evidence on mixing the vaccines from Spain was “very exciting” but the study was small.

“The fact that they are now being repeated will probably ultimately lead to us actually changing what we do but at the moment, the TGA has to be satisfied that it is sound enough for them to change the recommendations.” Dr Grenfell said.

Australian National University infectious diseases expert Professor Peter Collignon agreed that mixing vaccines was an option.

“The real problem with the AstraZeneca vaccine is that your risk of clotting is, highest with your first dose. So if you had a first dose and haven’t developed a clot, well, the risk from your second doses is minimal,” Prof Collignon said.

Originally published as Aussies given AstraZeneca should get Pfizer as their second jab