Washington: Johnson & Johnson company had temporarily halted its Covid-19 vaccine trial on Monday because one of its participants had become sick.

The company in a statement said that “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 pause means the online enrollment system has been closed for the 60,000-patient clinical trial while the independent patient safety committee is convened.

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 started recruiting participants in late September, with a goal of enrolling up to 60,000 volunteers across more than 200 sites in the US and around the world.

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