WASHINGTON, Oct. 12 (Reuters) - Johnson & Johnson said on Monday (Oct 12) it has temporarily paused its COVID-19 vaccine candidate clinical trials due to an unexplained illness in a study participant.

The participant's illness is being reviewed and evaluated by an independent data and safety monitoring board, as well as the company's clinical and safety physicians, it said in a statement.

"Adverse events – illnesses, accidents, etc - even those that are serious, are an expected part of any clinical study, especially large studies," said the company.

"Based on our strong commitment to safety, all clinical studies conducted by the Janssen Pharmaceutical Companies of Johnson & Johnson have prespecified guidelines.

"These ensure our studies may be paused if an unexpected serious adverse event that might be related to a vaccine or study drug is reported, so there can be a careful review of all of the medical information before deciding whether to restart the study."

Last week, the European Union announced it has sealed a deal with Johnson & Johnson to supply up to 400 million doses of its potential COVID-19 vaccine, as the bloc builds up stocks amid a global scramble to secure shots.

The deal is its third advance purchase contract with makers of COVID-19 vaccines after deals with AstraZeneca and Sanofi, bringing the number of doses secured by the EU for its population of 450 million to 1.1 billion.

Under the terms of the deal, the 27 EU states will be able to order up to 400 million doses of the potential vaccine after it is authorised by the EU medicine regulator.

To secure the vaccines, the EU made an undisclosed down payment to Johnson & Johnson, which confirmed the deal in a statement in which it reiterated plans to allocate up to 500 million additional doses to poorer countries from mid-2021.