28 Nov 2020

Australia's Oxford-AstraZeneca Covid-19 vaccine choice questioned as experts highlight 'shaky' science

4:28 pm on 28 November 2020

Sitting in his home in New York, Geoff Porges is a long way from his family in Orange, in regional New South Wales.

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Photo: Verwendung weltweit/ AFP

In fact, during 2020, it has never felt further away for Dr Porges, a vaccine expert of 25 years and a director of therapeutics research at the one of the world's leading healthcare investment banks.

And although he may be a long way away, this week Dr Porges made comments that reverberated back to his country of birth.

On Monday night Australian time, the AstraZeneca-Oxford University vaccine candidate, one of the Covid-19 vaccines the Australian Government committed to in a multi-billion-dollar deal, released its first interim results from its phase 3 trials.

At first glance the results were lauded, with the company claiming one dosing option provided 90 percent protection against Covid-19.

The Australian Government declared it a "very good result" that will help create a "fully safe Australia".

But Dr Porges wasn't convinced.

"We called it first," he told the ABC.

"We said, 'we think the company [AstraZeneca] has embellished the data'.

"And we said we didn't think it will get approved in the US.

"People were incensed with our first statements, but I think as more information has come out, more people are in agreement with us."

As this week rolled on, Dr Porges' comments have been vindicated.

Pressure has been mounting on the company all week, with a stream of scientists and researchers across the world joining Dr Porges' initial assessment.

Some labelled it "shaky science", while others questioned the legitimacy of the data released by the company.

Now, critically, the regulators are becoming involved.

And the issue, it seems, all comes down to a curious mistake.

Dosing by accident

The interim results of the phase 3 trial found the Oxford-AstraZeneca vaccine was 62 percent effective in people who received two doses.

But when volunteers were given a half dose followed by a full dose, that efficacy shot up to 90 per cent.

The company later acknowledged that the half dose was a "manufacturing issue" and given to the trial participants by mistake.

It also revealed only 2741 people had been given the half dose while 8895 people received the two full doses.

Facing increasing pressure to clarify the data, AstraZeneca chief executive Pascal Soriot said on Friday it would now likely conduct a new global clinical trial to assess the vaccine's efficacy.

However, he claimed he did not expect that to delay regulatory approval in Britain or the EU, despite the UK authorities on Friday openly questioning whether the vaccine meets "rigorous safety standards".

In the US, the Food and Drug Administration is another story.

Experts say that agency may take longer to approve the Oxford-AstraZeneca vaccine - if at all - given there are questions over the results, and parts of the trial were carried out in different countries.

In Australia, the Therapeutic Goods Administration makes decisions on the safety and efficacy of vaccines to be rolled out to the population.

It is often guided by international approvals in the US and the UK and is currently assessing the Oxford-AstraZeneca vaccine - which the Australian Government has committed to buying 33.8 million doses if approved - through what is known as "provisional determination".

The TGA did not answer specific questions from the ABC on whether the two doses seen in the data would affect the approval process.

Health Minister Greg Hunt also did not answer specific questions from the ABC on the developments with the Oxford-AstraZeneca vaccine this week.

However, speaking at a press conference on Friday, he said he was expecting "ups and downs" in the process.

He described the TGA as "the best regulator in the world" and said Australia's vaccine timeframe - scheduled for first rollout in March - was "unchanged".

But it is still unclear which of the four vaccines the Australian Government has invested in will be the one to roll out in March.

"Australia will not approve [a vaccine] unless we are absolutely convinced that a vaccine is both safe and effective," Hunt said.

"The data on all of the leading vaccines has been good, and I'm looking forward to more positive news on other vaccines in coming weeks on preliminary briefings that we've had."

But some vaccines experts are less convinced.

"[AstraZeneca] hasn't handled it the best," RMIT immunology and vaccine expert Kylie Quinn said.

"The error in the dosing is disappointing, disappointing to hear that that would happen at this particular point in time.

"But this whole situation highlights the importance of clear communication of exactly what's being done.

"And I hope in one respect the reaction [across the world] reassures the community how much scrutiny there is, and that by the time it gets approved by a regulatory body we can be reassured their vaccines have gone through a very high level of scrutiny:"

AstraZeneca chief executive Pascal Soriot.

Photo: Yan minglei - Imaginechina / AFP

Vaccine expert and virologist Tony Cunningham said it was too early to tell how the dosing issue with the Oxford-AstraZeneca vaccine could impact approval in Australia until its whole phase 3 trial results were known.

Those results, which assess 40,000 people, are expected before Christmas.

Prof Cunningham said he had never seen a trial "polluted" like this before.

"But I have seen what's known as 'adaptive trials'," Prof Cunningham said.

"This is where a change can be built in and you may change the doses during a trial.

"So perhaps they [AstraZeneca] are planning to do that and enable them to focus the half dose on a country where the trial is still going.

"That may be what they're suggesting they'll do, or they may go about starting a whole 'new trial'."

Prof Cunningham said it was unlikely, however, that safety would be affected by the two dosing regimes.

And, he said, even the 62 percent efficacy reported by the company in the two does regime was above the 50 percent required by most authorities - it was just well below the "incredible" 95 percent efficacy reported by Moderna and Pfizer earlier this month.

"But what happened this week is most definitely a sign of the times, the urgency of what we're dealing with," he said.

"It's a pretty important vaccine for Australia, and we wait with great interest to see the properly peer-reviewed reports."

Vaccine development still 'extraordinary'

Back in New York, Dr Porges said he was worried about how "consumer confidence" in vaccines would be impacted following AstraZeneca's reporting this week.

"Confidence comes from transparency of communication and clarity of communication," Dr Porges said.

"You need to be completely honest about what you're sharing and really clear about the information.

"And I think AstraZeneca, at the very least, violated those two tenets."

But, he said, there was still time for the company to recover.

And, like most people, he's waiting patiently and with excitement for a vaccine to come.

"I usually come back to Australia three or four times a year," he said. "But not this year, obviously.

"And although there have been issues this week, when you think about it, where we have got to after nine months is incredible.

"We have three vaccines well advanced, and two [Pfizer and Moderna] at 95 percent efficacy - that is quite extraordinary."

-ABC

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