Global COVID-19 Vaccine Frontrunner Halts All Trials After Suspected Adverse Reaction Investigated

One of the global frontrunners in the race to produce a working vaccine in the fight against COVID-19 has suffered a setback in its final stages of development. Pharmaceutical giant AstraZeneca was developing the drug in partnership with the University of Oxford when one of its volunteers came down with a severe illness during clinical trials.

AstraZeneca’s chief executive, Pascal Soriot, confirmed that the UK based female candidate was diagnosed with transverse myelitis, a rare but serious inflammatory syndrome that affects the spinal cord. The woman’s specific symptoms are unknown, but the condition itself can cause pain, muscle weakness and in the worst case, paralysis. Whilst it is often triggered by a viral infection, it can also be caused by immune system disorders. Most patients do recover, but some can end up with significant disabilities.

At this point in time, it is unclear whether the trial volunteer’s illness directly resulted from the vaccine they’d been administered, and AstraZeneca says it’s possible this illness could be unrelated. The trial was paused once already in July when a candidate developed neurological symptoms – these symptoms however were later found to be as a result of multiple sclerosis rather than anything to do with the vaccine itself.

An independent investigation is taking place to ascertain the cause of the volunteer’s illness, but in the meantime, the trial of one of the world’s most promising vaccines was paused globally. AstraZeneca started recruiting up to 30,000 people in the United States alone to come on board its phase 3 clinical trial of COVID-19 vaccine candidate AZD1222, whilst other trials have been ongoing in Brazil, South Africa, and the UK since the early summer with around 17,000 participants. The clinical trials are divided into three stages, with the UK trial already in phase three and looking to give a definitive evaluation of the drug’s effectiveness. Previous stages have already assessed the drug’s safeness and possible side-effects but within smaller-sized control groups.

When reached for comment, AstraZeneca described the pause as a “routine action” which must occur whenever “a potentially unexplained illness” arises. Researchers from outside of the study say this pause is not something to be alarmed about, primarily due to the large working numbers of the study. If anything, it is reassuring that the company has halted the trial to figure out the source of the issue, as this demonstrates a prioritisation of safety over speed. This comes after AstraZeneca, alongside nine other biopharmaceutical companies signed a pledge to uphold the integrity of the drug development process in the competition to manufacture the first approved COVID-19 vaccine.

Once the UK regulatory agency that is overseeing the vaccine development (the Medicines and Healthcare Regulatory Agency) has given the go-ahead, the trials will be green-lit to begin again. AstraZeneca has said that in the meantime, they are “working to expedite the review of the single event to minimise any potential impact on the trial timeline.”