China’s COVID-19 vaccine faces setback; Trials halted in Brazil

Because of a significant adverse event, the final-stage trial of a Chinese frontrunner vaccine candidate has been halted in Brazil.

This is the first time that any of the rapidly evolving COVID-19 shots from the Asian nation has experienced such a setback.

Testing of Sinovac Biotech Ltd.’s Coronavac vaccine was suspended in Brazil following an incident that occurred on October 29, the Brazilian Health Agency recently said, without providing any further specifics of what happened. The research has been interrupted in compliance with regulations, while the agency analyzes whether the study can proceed, it said.

Instituto Butantan of Sao Paulo, which partnered with Sinovac to produce the vaccine locally, said it was surprised by the decision and, in a statement, said that it is looking into details of what happened in the study. In an interview, director Dimas Covas said that one volunteer died during the trial, but that the death was not related to the vaccine.

In large-scale drug trials, interruptions to investigate significant adverse effects are not unusual and two western developers, UK-based AstraZeneca and US-based Johnson & Johnson, have halted their vaccine trials in recent months because of such occurrences, only to restart them after investigation.

But China has already begun administering its vaccines, including Coronavac, to hundreds of thousands of people under the emergency use approval, making the prospect of detecting a safety issue more alarming at this stage.

Last month, the Chinese Ministry of Science said its companies had inoculated around 60,000 volunteers in final-stage trials, but no cases of serious adverse effects were reported. In drug trials, significant adverse events could include death, immediate risk of death, long-term or extreme incapacitation and hospitalization.

Chinese vaccine developers have been at the forefront of the global race in order to create a successful immunization against the virus. As countries look to move past COVID-19 and re-open their markets more definitively, the push has taken on vital significance. Global players have compressed vaccine development processes that typically take years into months, encouraged by policymakers seeking a fast fix to the pandemic that has sickened more than 50 million people globally.

The Chinese setback comes as Pfizer Inc. and BioNTech SE released early findings showing that a vaccine they are developing prevented more than 90% of symptomatic infections in the trial of tens of thousands of volunteers, boosting hope for a quick neutralization of COVID-19.