U.S. pharmaceutical giant Johnson & Johnson paused its late-stage clinical trials of its COVID-19 vaccine after a participant was diagnosed with an unexplained illness.
The pause was first reported Monday by the health care news website Stat, which obtained a document the company sent to outside researchers.
Johnson & Johnson had just launched its wide scale testing of its single-dose experimental vaccine. The trial involves 60,000 volunteers across more than 200 locations in the United States and internationally, including Argentina, Brazil, Chile, Mexico and South Africa.
The company said in a statement that so-called “adverse events” such as illnesses and accidents are an expected part of a clinical study, especially with such a large number of participants. It also said the hold was a “study pause” and not a “clinical hold” which is imposed by a formal health regulatory agency.
Because it can be administered in a single dose, Johnson & Johnson’s vaccine has significant advantages over the other three potential vaccines, which require two doses. The single-dose vaccine would not have to be kept frozen in ultracold temperatures, making it easier to utilize in a mass immunization campaign.