Ann: POSITIVE FDA GUIDANCE FOR COVID-19 CLINICAL PROGRAM, page-358

Footmax

I doubt that the recent awareness of a link between higher GBS cases and AZ first dose had any bearing on switching to an alternative vaccine for boosters, primarily because the GBS scenario has come about after the vaccine regime, and therefore the GBS scenario cannot be a cause of something that occurred prior.

Rather, it was well established early in the global vaccine rollout that a mixture of a viral vector vaccine, like Astra Zeneca for the fist dose, followed by an mRNA vaccine, like Moderna or Phizer, created a better immune response than a regime from only one type of type of vaccine. Early studies done in Spain, Germany, Canada, and Sth Korea established this advantage and Angela Merkel, the then German Chancellor, and physicist by training, had the mixed regime early in 2020. It became standard protocol in many countries, but not Australia. The only occasions that a mixed vaccine regime could (can) be used in Australia was if the patient had arrived form overseas with having one prior vaccine that was not available in Australia, like the Johnson and Johnson, resulting in them not being able to have the same here again. As such, their only option was for a different second dose. Also, in cases where there had been a bad reaction to a first dose, a different second dose could be administered.

Not mixing vaccines until the booster stage in Australia was another example of the poor rollout here. You'll recall that we initially had none to little mRNA (when the government rejected 20 million doses from the US), but abundant Astra Z from import and local production, but unpopular due to the potential, as rare as it was, of thrombosis and/or death occurring. Once we did obtain the mRNA's, which were preferable to the population, we should have adopted the mixed vaccine regime, with an AZ for first dose, and an mRNA for second, which was the proven best variation. This would have had improved the rollout for several reasons.

Firstly, there would have been a better acceptance in receiving AZ when it was followed by mRNA that produced a better overall health outcome.
Secondly, it would have eased the burden on the limited, but in demand, mRNA's.

My guess as to why the government did not develop the mixed dose regime apart from those abovementioned special cases, was because by the time that the mRNA's here were being administered, the roll-out was more less on track, and the government was therefore recovering from their rollout failure. The last thing they were going to do then was to make a significant change to the system (even if it would have provided a world's best practice health outcome).

Anyway, that's all history now....... sought of.

Not long now.