Making good use of the AstraZeneca in which we are ‘awash’

Jul 28, 2021

Thanks to the Delta variant, the Covid-19 pandemic is now a national crisis. If the vaccine roll-out can find both the urgency and the administrative efficiency required, the immediate challenge stemming from an excess supply of AstraZeneca and an acute shortage of Pfizer can be met. While steps are being taken to divert Pfizer from second doses to first, the large numbers who are waiting for the second AstraZeneca can be invited to have their second after less than 12 weeks have elapsed.


With just one critical piece of scientific evidence plus considerably more administrative dexterity than has been shown to date, much of the AstraZeneca already available can be used effectively in the next 4 to 6 weeks. This would utilise a valuable resource, boost the national vaccination rate, and provide time for an information, incentive and campaigning blitz to encourage greater confidence in AstraZeneca in the future.

The evidence available online is that the first AstraZeneca jab results in something between “barely any” efficacy against infection (as reported in a recent article in Nature) and 30% (as reported in an interview last week on RN with Assoc. Prof. Margie Danchin). For immunity given by the first AstraZeneca jab against hospitalisation due to Covid, the range is from “barely any” to 71%.

Those same two sources report the efficacy of the second AstraZeneca vaccination, given 12 weeks after the first, results in 67% against infection, and 92% against hospitalisation.

If the relationship between time and the effect of bringing forward the second jab is a straight line pro rata, the efficacy vis-à-vis infection after 4 weeks would be 42%, and against hospitalisation, 78%.

The significant discrepancy between various reported studies of the efficacy after the first jab (‘barely any’ to 30%; and barely any to 71%) are a problem – but not in the context of the proposal described in this piece. That is because the people involved in it are those who have already had the first. The decision they would be asked to make is determined by the evidence about the effect of the second.

Belief in the case that reducing the gap to less than 12 weeks has little impact on efficacy is strengthened by a heroic use of anecdotal evidence – as distinct from good science. On 11 July Norman Swan reported on Twitter that he had just had his second AstraZeneca vaccination:

“A bit less than nine weeks since the first. Willing to accept a little lower immune response to get protection against severe disease.” (Norman Swan, 11 July 2021)

If one needs to make a heroic assumption based on a single case, in my view there could hardly be anyone in a better position of trust than Dr Norman Swan.

There have been 6.1 million doses of AstraZeneca given, the majority of them to people over 60, but a significant number (c. 900,000) to 50-60 year olds and a smaller number of people younger still. These younger people are those who responded positively to the (controversial) encouragement by the Prime Minister on 28 June to make ‘a risk-based decision’ following consultation with the a GP  – who would be indemnified against any risks resulting from an AstraZeneca vaccination to persons under 60 who requested it.

There is about a 4-8 week window of opportunity for a rapid surge in uptake of AstraZeneca. The 6.1 million are people who have already demonstrated their readiness to take AstraZeneca – although some may now be more AstraZeneca shy than they were initially. Given the 12-week delay normally required, and the fact that AstraZeneca jabs only started in early March, there must be 3 to 4 million who have got some further time to wait before their regular second, all of whom could be encouraged to bring forward that second. (Some have been turned off AstraZeneca so much that they have postponed their second.)

The threshold fact is what the science tells us about the loss of efficacy per week of advancement.

If the evidence is that there is just a modest loss, then we could be sure that a significant proportion of the 3 to 4 million would volunteer to sacrifice some immunity for temporal (and national community) gain. Some would go out of their way and take on board some level of risk to contribute to a demonstration of Australia’s community spirit. And it would give our governments another string to their bow – although to date they have shown themselves to be pretty hapless archers.

To be successful the roll-out would need effective national leadership to:

  • put the initiative firmly and clearly on the public agenda;
  • back the announcement with a clear statement from a reputable body or bodies about    how much efficacy is lost per week from bringing the second dose forward;
  • get it done – through the hubs specially established, through GPs and maybe through pharmacists, who are now joining the campaign in number.

The initiative could be one of the special reserves of pharmacy in the rollout, giving them a greater sense of ownership and investment in the national operation.

Whether pharmacists and a special role or not, the administrative dexterity required would include the capacity to contact all of those who have had a first AstraZeneca vaccination inviting them to have their second before 12 weeks have elapsed.

To date, very little dexterity and absolutely no urgency have been in evidence in the vaccine program. But it is not too late to discover and demonstrate such characteristics.

So while the crisis management is diverting scarce Pfizer resources from second vaccinations to first, a portion of the 3 to 4 million people who have already demonstrated their willingness to have AstraZeneca can be used to mop up the domestically-produced vaccine in which the nation, paradoxically and tragically, is awash.

Even if the news about the immunity lost per week is not so benign, it is likely that a significant proportion of this cohort would provide an immediate and significant boost to the overall coverage of vaccination and confidence in AstraZeneca. Many would be glad to do their bit to attest to the fact that Australia is a strong community and would be happy to receive a call to bring forward their second AstraZeneca jab.

Others in that cohort would make the quite rational decision to trade a little lower immunity for more immediate coverage.

There is limited time to invest in this fix for a part of the crisis we face.

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