Leiden firm's coronavirus vaccine trial to restart after patient's stroke: Report

Testing was set to resume on a SARS-CoV-2 coronavirus vaccine developed by a laboratory in Leiden for its parent company, Johnson & Johnson, the company said in a statement. The Phase 3 trial was halted after one test subject suffered a stroke, according to the Washington Post.

Two anonymous sources told the newspaper that the stroke was not believed to be connected to use of the vaccine. The study run by Janssen Vaccines in the Netherlands was stopped on October 12 after the man became ill.

Researchers at Janssen were still being kept in the dark about whether or not the study participant who had the stroke received the vaccine or a placebo, the company said publicly. "This is to maintain the integrity of the data, which is essential to establish the safety and efficacy of the vaccine candidate," Johnson & Johnson said in a statement.

His stroke may have been caused by an infection, the sources said. Details of his case were scrutinized, and compared against a database of a hundred thousand other candidates who were vaccinated using the same technology, the newspaper reported.

"After a thorough evaluation of a serious medical event experienced by one study participant, no clear cause has been identified. There are many possible factors that could have caused the event. Based on the information gathered to date and the input of independent experts, the Company has found no evidence that the vaccine candidate caused the event," according to the Johnson & Johnson statement

The company was beginning preparations to resume the vaccine study, and was meeting with the U.S. Food and Drug Administration about approval. "Discussions with other regulators around the world to resume the clinical trial program are progressing."

The Janssen coronavirus vaccine is one of six pre-purchased in deals negotiated in part by the Dutch government on behalf of the European Union. The first of these, a vaccine developed at Oxford University for AstraZeneca, was also going to resume U.S. trials after a British candidate was likely diagnosed with transverse myelitis, a spinal cord inflammation which can cause severe neurological problems.

The advanced AstraZeneca trial already restarted in Brazil, Japan, South Africa and the United Kingdom.