Following a swift independent investigation by the Medicines Health Regulatory Authority (MHRA), large-scale Phase 3 trials for a COVID-19 vaccine developed by scientists at the University of Oxford, are recommencing across the United Kingdom after a suspected adverse reaction triggered a global halt to trials last week.
This COVID-19 vaccine, dubbed AZD1222, aka ChAdOx1 nCoV-19, is being developed in association with biopharmaceutical company AstraZeneca and is one of several currently in late-stage Phase 3 trials. The voluntary pause was triggered on September 6 after a standard review identified an adverse reaction in one subject.
“Globally some 18,000 individuals have received study vaccines as part of the trial,” the University of Oxford said in a recent statement. “In large trials such as this, it is expected that some participants will become unwell and every case must be carefully evaluated to ensure careful assessment of safety.”
The details of the adverse reaction are still unclear but StatNews has reported the CEO of AstraZeneca said to investors privately the subject was experiencing neurological symptoms consistent with an inflammatory spinal condition called transverse myelitis.
It is standard procedure to pause clinical trials when abnormal conditions appear. Subsequent investigations then consider whether the drug, or vaccine, being tested can be linked to the negative health condition.
In this instance, a rapid review by the MHRA led to a recommendation the trials be restarted. As the MHRA only regulate activities in the UK, the vaccine trials halted in other parts of the world are still on pause until their respective regulatory bodies complete investigations.
“AstraZeneca and the University of Oxford, as the trial sponsor, cannot disclose further medical information,” AstraZeneca said in a statement. “All trial investigators and participants will be updated with the relevant information and this will be disclosed on global clinical registries, according to the clinical trial and regulatory standards.”
Despite the intense attention on the development of this particular COVID-19 vaccine, it is important to note these kinds of clinical trial pauses are routine. In fact, it has been reported this same vaccine trial was temporarily halted back in July after a subject was diagnosed with multiple sclerosis. The trial was swiftly restarted after investigations determined the illness was not related to the vaccine.
Hassan Valley, an epidemiologist from La Trobe University, suggests rather than this transitory pause being a cause for concern it should instead offer reassurance that this vaccine trial is being conducted using optimal safety precautions.
“…the halting of the trial should reassure us that the proper processes and safety precautions are being followed, despite the urgency to find an effective vaccine to respond to this pandemic,” says Valley. “The investigators need to go through the process of trying to work out what may have happened in this situation before progressing with this trial. Adverse reactions in these sorts of trials do occur and this does not necessarily mean that there is a major problem with the vaccine.”
The ongoing Phase 3 Oxford COVID-19 vaccine trial spans five continents: the United States, Brazil, South Africa, the UK and India. Researchers involved in the project are confident of having some idea of the vaccine’s efficacy by the end of 2020, and hope a broad public roll-out of the vaccine could begin in the first half of 2021.