Vaccine Update: Johnson & Johnson has temporarily halted its COVID-19 vaccine trial because one of its participants had become sick. The pause means the online enrollment system has been closed for the 60,000-patient clinical trial as an independent patient safety committee is convened.

“We have temporarily paused further dosing in all our Covid-19 vaccine candidate clinical trials, including the  Phase 3 ENSEMBLE trial, due to an unexplained illness in a study participant,” the company said in a statement.

Accidents and other so-called adverse events “are an expected part of any clinical study, especially large studies,” the company said in the statement, adding that its physicians and a safety monitoring panel would try to determine the reason behind the illness, reported news agency Associated Press.

This is the second such instance in which trials for a late-stage study have been halted. AstraZeneca and Oxford University’s vaccine testing is on hold in the US as officials examine whether an illness in its trial poses a safety risk. In other places, however, trials have resumed.

The interruption implies the online enlistment system has been shut for the 60,000-patient clinical preliminary while the autonomous patient safety committee is gathered. 

J&J said that serious adverse events (SAEs) are “an expected part of any clinical study, especially large studies.” Company guidelines allowed them to pause a study to determine if the SAE was related to the drug in question and whether to resume study.

The J&J Phase 3 trial had begun enlisting members in late September, J&J was aiming to enroll 60,000 volunteers to prove if its single-dose approach is safe and protects against the coronavirus in excess of 200 destinations in the US and around the globe. 

The other countries where the trials were taking place are Argentina, Brazil, Chile, Colombia, Mexico, Peru and South Africa.