China's Sinovac hit by late-stage COVID-19 vaccine halt after reports of a death in Brazilian trial

BD vaccine syringe
(BD)

Sinovac Biotech has seen a phase 3 trial of its pandemic vaccine hopeful Coronavac stopped in Brazil after reports of a serious safety concern, with one report stating a death is involved but was not in the vaccine arm.

Details are still a little vague, but Bloomberg and CNN say Brazil’s National Health Surveillance Agency has stopped the trial due to the “occurrence of serious adverse event in one of the volunteers in Brazil.”

No further information has been shared, though Director Dimas Covas said in a TV interview via Bloomberg that one volunteer in the trial has died, but the death was not a result of the vaccine.

This comes less than a day after Pfizer released an interim, top-line look via a press release of it and partner BioNTech’s COVID-19 vaccine, which showed 90% efficacy, creating a solid bounce in their respective stocks, the biotech industry in general and global stocks.

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But it also comes amid several similar halts for safety that have hit AstraZeneca and its partner, the University of Oxford, as well as Johnson & Johnson. These are fairly common in large trials and par for the course, and they typically don’t stop a trial or drug/vaccine in its tracks. Both companies have since resumed their tests.

Even if the safety issue is not related to the vaccine, a study must still be halted and investigated to see what happened. This is still, however, a setback for one of China's leading vaccine candidates, and it comes as China has in fact already starting inoculating large swaths of people across the country with the vaccine.

There is a political element wedded into the story: Brazilian President Jair Bolsonaro has in the past been critical of the vaccine, saying Brazilians won’t feel safe using it “due to its origin.”

In a brief statement, Sinovac said: “After communicating with the Brazilian partner Butantan Institute [which is helping with the trial], we learned the head of Butantan Institute believed that this serious adverse event (SAE) is not related to the vaccine.

“Sinovac will continue to communicate with Brazil on this matter. The clinical study in Brazil is strictly carried out in accordance with GCP requirements and we are confident in the safety of the vaccine.”