AstraZenecaAstraZeneca (NYSE:AZN) announced today that it voluntarily paused the trials for its COVID-19 vaccine candidate after an unexplained illness.

The company said in a news release that a standard review process was triggered so an independent committee could review safety data surrounding a single event of an unexplained illness that occurred in the UK Phase III trial for the AZD1222 vaccine being developed in collaboration with Oxford University.

“As part of the ongoing randomized, controlled global trials of the Oxford coronavirus vaccine, our standard review process was triggered and we voluntarily paused vaccination to allow review of safety data by an independent committee,” an AstraZeneca spokesperson told Drug Discovery & Development in a statement. “This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials. In large trials, illnesses will happen by chance but must be independently reviewed to check this carefully. We are working to expedite the review of the single event to minimize any potential impact on the trial timeline.

“We are committed to the safety of our participants and the highest standards of conduct in our trials.”

StatNews reported that, while the nature of the unexplained illness and other details surrounding it were not disclosed, a person close to the situation told the outlet that the involved participant is expected to recover.

“At AstraZeneca we put science, safety and the interests of society at the heart of our work,” AstraZeneca CEO Pascal Soriot said in the news release. “This temporary pause is living proof that we follow those principles while a single event at one of our trial sites is assessed by a committee of independent experts. We will be guided by this committee as to when the trials could restart, so that we can continue our work at the earliest opportunity to provide this vaccine broadly, equitably and at no profit during this pandemic.”

In July, AstraZeneca and Oxford published early-stage results from their Phase I/II clinical trial of the SARS-CoV-2 vaccine candidate, confirming that they observed safety and strong immune responses.

The vaccine candidate has since moved into Phase III trials, although the company last month denied rumors that it is involved in talks with U.S. authorities about an emergency use authorization (EUA) for the vaccine after President Donald Trump has insinuated that the administration is looking to fast-track a vaccine.

In a move likely in response to the Trump administration’s eagerness to get a vaccine on the market, AstraZeneca was one of nine drug companies that yesterday pledged to ensure safety with a potential COVID-19 vaccine and only submit for approval or emergency use authorization (EUA) after demonstrating safety and efficacy through a Phase 3 clinical study designed to meet the requirements of the regulatory bodies, essentially confirming that no vaccine will be rushed through the process.