Dr Norman Swan cuts through the confusion about AstraZeneca

DR NORMAN SWAN, REPORTER: Two weeks ago the Prime Minister faced a backlash after his comments which seems to contradict the expert medical advice that Pfizer was the preferred vaccine for people aged under 60.

SCOTT MORRISON, PRIME MINISTER: The ATAGI advice talks about a preference for AstraZeneca to be made available to those as preferred for those over 60 but the advice does not preclude persons under 60 from getting the AstraZeneca vaccine.

NORMAN SWAN: We’ve been on a vaccination roller-coaster for months now.

Yesterday the expert medical advice from ATAGI changed, largely because of the latest outbreak of the Delta variant. That shifted the whole risk calculation for the rare side effects linked to the AstraZeneca vaccine.

The Technical Advisory Group on Immunisation, known as ATAGI now says that in an outbreak zone, people younger than 60 should reassess the rare risk of clots from Astra verses the benefits of COVID protection.

Associate Professor Chris Blythe is co-chair of ATAGI.

ASSOC. PROF. CHRIS BLYTH, CO-CHAIR OF ATAGI: Importantly, many people are, particularly those 40 to 59, eligible for the Pfizer vaccine and importantly, that is our preferred vaccine under the age of 60 but in the setting of outbreaks, there is likely to be benefit of AstraZeneca vaccines, particularly those at greatest risk and that is the balance people need to consider.

NORMAN SWAN: But that didn’t stop the Prime Minister venting his frustration on commercial radio today.

SCOTT MORRISON (On 2GB): ATAGI has been very cautious, and that had a massive impact on the rollout of the vaccine program. It really did. It slowed it considerably and it put us behind and we wish that wasn’t the result, but it was.

NORMAN SWAN: We interviewed Chris Blyth this morning before these comments were made by the Prime Minister but we did ask him if ATAGI felt under any pressure from the Government.

CHRIS BLYTH: Decisions are made independent of government and importantly, we provide all of those recommendations to government. How that informs then the rollout strategy clearly has a number of layers on top of the health advice, but we provide health advice.

DR KERRY CHANT, NSW CHIEF HEALTH OFFICER: We are recommending that whilst the interval was at three months, at this time, because we are seeing case numbers high, we want to get people to come forward and you can get vaccinated around that six-weeks mark.

NORMAN SWAN: The other new advice from ATAGI was that in a Delta outbreak, people who have had their first Astra dose should get their second dose sooner, within four to eight weeks rather than three months.

CHRIS BLYTH: ATAGI has always said, although the preferred interval is 12 weeks, in the settings where the risk is greater and the risk of exposure is greater, the interval should be shortened.

NORMAN SWAN: You could be forgiven for being confused because for months now we’ve been told that a 12-week gap between AstraZeneca doses gets you maximum immunity.

The obvious question then is whether an earlier dose lowers your protection?

Professor Terry Nolan is a former chair of ATAGI and a vaccine expert.

PROF. TERRY NOLAN, THE PETER DOHERTY INSTITUTE: We’re dealing with very imperfect or imprecise data that doesn’t give us a clear black and white answer.

NORMAN SWAN: What Professor Nolan is referring to is that the data suggesting a better immune response with a 12-week gap were based on small numbers in a clinical trial of the Astra vaccine last year.

What was not at all clear in the findings was the difference if you had your second dose at six or eight weeks. In fact the evidence, such as it is, is reassuring.

TERRY NOLAN: It’s not materially very large, but more importantly it is quite imprecise and it also says nothing about any difference in efficacy against severe disease, which we don’t know about.

NORMAN SWAN: The point we need to focus on is whether with the Delta strain a shorter gap still gives good protection against serious illness.

Chris Blyth believes it does.

CHRIS BLYTH: What we’re recommending is actually that short term protection you get from your second dose in an outbreak situation is more important than any potential long-term effectiveness you get from a delayed interval.

NORMAN SWAN: We are not the only nation in a race to get immunised with limited vaccine supplies. Professor Terry Nolan proposes a solution to this.

TERRY NOLAN: We do the same as they did in England and also in Canada. We have sparse supply, we make a decision to get more people immunised now imperfectly with only one dose and get them their second dose just a bit later.

NORMAN SWAN: Terry Nolan is suggesting lengthening the time between doses of the Pfizer vaccine from three to six weeks. This would release stock held back for second doses and get first shots into the maximum number of people as quickly as possible.

TERRY NOLAN: I’m recommending this idea be considered by ATAGI and by government as a way of just getting us through this initial pipeline, this bridge over the next two months or so until we have got much more plentiful supply of both Pfizer and Moderna vaccines.

NORMAN SWAN: It’s understood that ATAGI has been discussing exactly this.

CHRIS BLYTH: The recommendation has always been that a Pfizer dose can be given between 19 and 42 days. So there is an interval there and that interval was provided to try and give flexibility to providers and to strategies as far as that.

As far as what the long-term impacts of that and the impacts on the rollout strategy, I will leave that to government.

NORMAN SWAN: The message in New South Wales and from today’s news in Victoria is that we need to think hard about this revised advice.

In New South Wales, if you are infected with the COVID-19 virus, your chances of ending up in ICU are 1 in 40. Those are not good odds compared to the 1 in 50,000 risk of getting a blood clot after receiving the AstraZeneca vaccine.