Nobody can know where the first safe and effective vaccine against Covid-19 will come from, warned one of the UK’s leading medical experts, as the trials of the frontrunner, from Oxford University, were put on hold.
The Oxford vaccine appeared to be storming ahead, amid hopes it would have the data to get it approved by a regulator before the end of the year. Last month, Donald Trump was said to be considering pushing for it to be fast-tracked in the US before the presidential election in November.
But the phase 3 trials, the final stage involving tens of thousands of people, have been paused because of the illness of one of the UK volunteers. Studies are also under way in the US, Brazil and South Africa, with a view to getting a quicker answer because of the greater numbers of cases in those countries.
Sir Jeremy Farrar, the head of Wellcome and an infectious diseases specialist, said vaccine development “is an inherently risky endeavour, and you cannot back on a single vaccine candidate. You have to have a portfolio, you have to be pragmatic that not all of these vaccines in late stage development will make it through.”
Safety is absolutely critical, he said. Large-scale trials and follow-up of people who have been vaccinated after licensing were vital.
Farrar, who is also a member of the government’s Sage scientific advisory body, called for scientists worldwide to share their data, as Oxford/AstraZeneca has. It is “absolutely critical that we know what’s happening in the US and Europe in China and Russia and everywhere else, developing these vaccines”.
No country should assume they can buy up the stocks they need and ignore the rest of the world, he said. “There is no value in vaccine nationalism. It’s not a way out of the pandemic. It won’t speed things up – in fact, it’ll slow things down. And we have no idea where the best vaccine that is safe and effective will come from.”
The UK health secretary, Matt Hancock, said he was not overly concerned about the decision by the pharmaceuticals firm AstraZeneca to halt vaccine trials, he said, adding that it had already overcome a similar delay.
“This is a normal part of a vaccine development that, when you find a problem, the system is paused while you investigate that particular problem,” he told LBC radio.
“What it underlines is that we won’t bring forward a vaccine unless it is safe, no matter how enthusiastic I am for a vaccine.”
Hancock told Sky News: “It is obviously a challenge to this particular vaccine. It’s not actually the first time it has happened to the Oxford vaccine and it’s a standard process in clinical trials.”
Asked if it was a setback, Hancock said: “Not necessarily – it depends on what they find when they do the investigation. There was a pause earlier in the summer and that was resolved without a problem.”
He told LBC the UK had “other irons in the fire”. The government has ordered 340m doses of six different vaccines, which was “far more” than was needed for the UK population, said Hancock.
“This is a pause not a stop so I am hopeful [AstraZeneca] will be able to resume but only if it is safe to do so.”
A spokesman for AstraZeneca, the company working with Oxford University, told the Guardian the trial had been stopped to review the “potentially unexplained illness” in one of the participants.
The spokesman stressed that the adverse reaction was only recorded in a single participant and said pausing trials was common during vaccine development.
An anonymous source familiar with the situation told the New York Times that the person with a suspected adverse reaction had been enrolled in a phase 2/3 trial based in the UK.
The volunteer had received a diagnosis of transverse myelitis, an inflammatory syndrome that affects the spinal cord and is often sparked by viral infections, according to the individual. Independent investigators have been called in to find out whether or not the condition is vaccine-related.