11 Sep 2020

Covid-19 vaccine: Pause to Oxford trial 'reassuring' - expert

12:36 pm on 11 September 2020

Development of a Covid-19 vaccine is still making strong headway despite a serious illness that led to a hold on a leading late stage trial, experts say.

A scientist is pictured at the Oxford Vaccine Group's laboratory facility at the Churchill Hospital in Oxford, west of London on June 24, 2020.

A scientist at the Oxford Vaccine Group's laboratory facility at the Churchill Hospital in Oxford, west of London in June. Photo: AFP

The Oxford University AstraZeneca trial was paused earlier this week after a person who received the vaccine in the UK was hospitalised with neurological complications.

The late-stage trials have been described by health experts as probably the world's most promising development toward a successful vaccine against Covid-19 and have been followed closely. A safety review to be conducted by an independent board of experts is to be conducted before the trial resumes.

But the delay isn't a reason to be discouraged, and indicates good things are being done behind the scenes, a New Zealand expert told Morning Report.

David Murdoch is a professor of Infectious Diseases at the University of Otago and a member of the Ministry of Health's Covid-19 Technical Advisory Group, he says his hopes for an early vaccine haven't been dimmed by the AstraZeneca trial pause.

"If anything this is really reassuring to everyone that there are rigorous processes in place, because there's been a lot of talk about these rushed vaccines, that they may be cutting corners in terms of safety - well certainly that's not happening, and this is a very rigorous process.

University of Otago professor of infectious diseases David Murdoch.

Professor David Murdoch. Photo: University of Otago

He says because phase 3 medical trials are tested against thousands of people a serious illness in a participant isn't unusual, and could be unrelated to the vaccine.

"This is vaccine's been through phase 1 and 2 trials without any safety issues being identified.

"Life happens and participants ... there will be some people who become unwell, and that's part of the normal study process, to identify and respond to any person who's unwell, and to investigate and see whether there might be any link to the vaccine. It really is a routine part of it, to follow this through, and the pause is not unusual."

'2021 vaccine still likely'

A vaccine is still likely to be available next year, despite the AstraZeneca delay, RNZ's First Up was told by Peter Doherty, a professor of infectious disease and immunology at Melbourne University.

He says while not many details are known about the illness in the AstraZeneca trial nothing released indicates serious hurdles.

Nobel prize winner in medicine Professor Peter Doherty

Nobel prize winner in medicine Professor Peter Doherty. Photo: Supplied.

"If it goes well, and if it's giving say 50 percent protection or somewhere up around there... I'd expect we'd be seeing them rolled out at least on an experimental basis to large numbers of people early next year."

He's still putting his money on the AstraZeneca vaccine to be ready first, but says trials for an RNA vaccine produced by Moderna in the US are also well into Phase 3 trials. And capacity is also in place for an Australian vaccine being developed at The University of Queensland to be available in large numbers by mid-2021.

"From what I understand a total of 8000 people in the [AstraZeneca trial] were either vaccinated with the new vaccine against Covid or they were injected with the meningococcal vaccine, and one person from the trial - we're told from unofficial sources - developed transverse myelitis, an inflammatory disease of the spinal cord.

"There is some linkage as a very rare occurrence between [transverse myelitis] and the meningococcal vaccine. We don't know if [the sick person] is in the group that got the Covid vaccine or the meningococcal vaccine, or some other placebo, all we know is there has been some problem."

The trial scientists will have stopped giving the new vaccine or the placebo to any more participants until a safety committee reviews what happened "and they're confident it's not a consequence; If their committee clears it, the vaccine trial will just go ahead", he says.

An illness in a participant doesn't necessarily spell out a problem with the vaccine, however there would be a problem if participants became ill because of a "confrontation" between the virus and the vaccine - if they became ill from contracting the virus after already being vaccinated.

"Because we haven't got any information on that yet in people - and these are people who are out there in the community who could potentially be infected."

Doherty says all vaccines in development aim to create immunity to part of the virus structure - the "spike proteins", which cover the surface of the virus and are used by the virus to attach to cells in the body and to enter them.

So the worst thing that could show up in any trials would be signs participants become more susceptible to the disease if they're immune to the Covid-19 spike protein because of a vaccine.

"That would be the real real worry, that's what would stop it. And actually if it stopped it for one vaccine, it might stop it for all vaccines," he says.

"So far we've seen no hint of that with either animal studies or... the big phase 3 trials. But the phase 3 trials are still in progress, it's still early and we haven't heard any ongoing results from them yet."

The AstraZeneca vaccine is the most promising trial purely because it's the furthest ahead in testing, Doherty says.

"They're leading in the sense they're the first off the block. That's not saying they're any better or any worse than any of the other vaccines that have been proposed - it's just they may get there first, they may be licensed first and as a consequence they may be available first."

Most of the vaccines in development are likely to be delivered as a primer injection and a booster injection given some weeks later, and would provide immunity for about a year. And Doherty says many of the vaccines have the potential to be used together, which could offer an advantage to develop strong immunity quicker.

Not always a fast and straight road - WHO

Deputy Director General of the World Health Organisation (WHO), Dr Soumya Swaminathan.

WHO deputy director general Dr Soumya Swaminathan. Photo: AFP

The pause on the trial should give pause for thought but shouldn't demoralise researchers, the World Health Organisation's chief scientist says.

"This is a wake-up call to recognise that there are ups and downs in clinical development and that we have to be prepared," Soumya Swaminathan told a virtual briefing from Geneva.

"We do not have to be discouraged. These things happen."

More than 900,000 people with the virus have died and 27.95 million people have been reported infected globally, according to a Reuters tally.

"It's a race against this virus, and it's a race to save lives. It's not a race between companies, and it's not a race between countries," added WHO's head of emergencies Mike Ryan.

WHO epidemiologist Maria Van Kerkhove said a combination of factors is helping reduce death rates in Europe, including finding cases earlier and better clinical care.

"We are in a better position to prevent the virus from infecting vulnerable populations," she said, cautioning, however, that the disease's long-term effects were still not known.

WHO General Director Tedros Adhanom Ghebreyesus, who on Thursday raised his fundraising plea to $US38 billion (NZ$57 billion) for the agency's ACT Accelerator program to fight Covid-19, called for global solidarity.

"What worries me the most is what I have been saying all along: a lack of solidarity," Tedros said.

"When we are divided, it is a good opportunity for the virus."

See all RNZ coverage of Covid-19

- RNZ / Reuters

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