AstraZeneca pauses Covid-19 vaccine trials after unexplained participant illness

Allie Nawrat 9 September 2020 (Last Updated September 9th, 2020 15:00)

Anglo-Swedish pharma giant AstraZeneca has voluntarily paused global late-stage trials of the investigational Covid-19 vaccine it is developing with the University of Oxford, AZD1222.

AstraZeneca pauses Covid-19 vaccine trials after unexplained participant illness
AstraZeneca is developing a Covid-19 vaccine with Oxford University called AZD1222. Credit: Shutterstock.

Anglo-Swedish pharma giant AstraZeneca has voluntarily paused global late-stage trials of the investigational Covid-19 vaccine it is developing with the University of Oxford, AZD1222.

The decision was made because of the unexplained illness of a trial participant and the need to allow an independent data monitoring committee to review the safety data. The committee will determine if the illness is directly linked with the Covid-19 vaccine.

The nature of the participant’s adverse reaction has not been disclosed, however the New York Times has reported that the trial  volunteer has been diagnosed with an inflammatory condition called transverse myelitis. AstraZeneca is yet to confirm if this is the case.

It is believed that the patient in question was involved in the UK arm of the trial. AstraZeneca’s Covid-19 vaccine is also currently involved in Phase III studies in the US, Brazil and South Africa.

In a statement, AstraZeneca explained: “This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials.” The pause will enable the company to ensure it can “maintain the integrity of the trial”.

“In large trials illnesses will happen by chance, but must be independently reviewed to check this carefully,” the company added in the statement.

The statement also noted that AstraZeneca is “working to expedite the review of the single event to minimise any potential impact on the trial timeline”. There were hopes that AstraZeneca’s vaccine could be approved by January 2021 and multiple countries – most notably the UK, Australia, Brazil and the US – have signed supply deals for this vaccine candidate.

Once the independent data monitoring committee has reviewed the data, according to the BBC medical editor Fergus Walsh, it will communicate its findings with UK healthcare regulator the Medicines and Healthcare products Regulatory Agency (MHRA), which will make the decision on whether to lift the suspension globally. This decision could potentially come within days.

In a statement, AstraZeneca CEO Pascal Soriot that this decision is linked to the company’s commitment “to put science, safety and the interests of society at the heart of our work. This temporary pause is living proof that we follow those principles while a single event at one of our trial sites is assessed by a committee of independent experts.”

The decision to pause the trial is in tune with a joint letter published late yesterday by nine Covid-19 manufacturers, including AstraZeneca, in which they publicly committed themselves to prioritise developing and studying Covid-19 vaccine candidates “in accordance with high ethical standards and sound scientific principles”.

Responses from scientists and politicians

There is general agreement that pausing the study is good practice and a routine part of vaccine clinical trials.

UK public health foundation Wellcome Trust’s head of vaccines Charlie Weller wrote in a statement published on Twitter: “Vaccines are among the most rigorously tested and monitored products in society and the Covid-19 vaccines should be no different. It is critical to quickly understand whether the illness has any relationship to the vaccine or the placebo and to share data openly.”

British Society of Immunology chief executive Dr Doug Brown agreed with this sentiment. In a published statement, Brown said: “Because safety is so critical, vaccine trials are incredibly complex and each vaccine goes through many stages of testing both in the lab and in clinical trials.

“What we are seeing with the news that the AstraZeneca–Oxford University coronavirus vaccine trial has been paused due to ill health in one participant is one of these safety procedures kicking in.

“This type of pause to a vaccine trial to investigate an unexplained illness is not an uncommon event and in fact it’s exactly what we should all want to see the vaccine researchers doing to ensure the safety of any potential vaccine above everything else.”

In an interview with LBC radio and reported by the Guardian, UK Secretary of State for Health and Social Care Matt Hancock stated he was not overly concerned about AstraZeneca’s decision.

“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,” Hancock said. “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.”

“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,” Hancock added.