LONDON (AP) — Oxford University says trials of a coronavirus vaccine that it is developing with pharmaceutical company AstraZeneca will resume, days after being paused due to a reported side-effect in a patient in the U.K.

In a statement, the university said in large trials such as this “it is expected that some participants will become unwell and every case must be carefully evaluated to ensure careful assessment of safety.”

It said that globally some 18,000 people have received the vaccine as part of the trial.

It would not disclose information about the patient's illness for reasons of participant confidentiality but insisted that it is “committed to the safety of our participants and the highest standards of conduct in our studies and will continue to monitor safety closely.”

Pauses in drug trials are commonplace.