The University of Oxford says trials of a coronavirus vaccine it is developing with pharmaceutical company AstraZeneca will resume days after being paused due to a reported side effect in a patient in the UK.

In a statement, the university said that in large trials « some participants are expected to feel unwell and each case must be carefully evaluated to ensure a careful assessment of safety. »

He said that around 18,000 people worldwide have received the vaccine as part of the trial.

Although it would not disclose information about the patient’s illness, an AstraZeneca spokesperson said earlier this week that a woman had developed severe neurological symptoms that led to the pause in testing.

The university insisted that it is « committed to the safety of our participants and to the highest standards of conduct in our studies and will continue to closely monitor safety. »

Pauses in drug trials are commonplace.

The study had previously been stopped in July for several days after a participant who received the vaccine developed neurological symptoms; it turned out to be an undiagnosed case of multiple sclerosis that was not related to the vaccine, the researchers said.

Late last month, AstraZeneca began recruiting 30,000 people in the US for its largest study of the vaccine. He is also testing the vaccine in thousands of people in Britain and in smaller studies in Brazil and South Africa. Several other vaccine candidates for COVID-19 are in development.

Dr Soumya Swaminathan, chief scientist at the World Health Organization, said the UN health agency was not overly concerned about the pause in the Oxford and AstraZeneca vaccine trial, describing it as « a wake-up call. » to the world community about the inevitable ups and downs of medical research.