China COVID-19 vaccine trial halted because of a death, unrelated to vaccine

Reuters with the update re this:

• China COVID-19 Vaccine Trial Halted in Brazil After Serious Adverse Event

Obviously, I don't have all the info on this yet, its still incoming. But I do wonder why the trial is halted if the death was unrelated.

Reuters amendment to the story now, comment from head of the Butantan Institute, not the Mayor of the city, with the comments

The Butantan Institute is doing the testing.

The clarification still doesn't explain the question why the test was cancelled if the death was unrelated.