American drug maker Johnson & Johnson has suspended its Phase 3 COVID-19 vaccine trial. The suspension came after a patient in the study had "unexplained illness."
A month ago, British drug-maker AstraZeneca also temporarily stopped its vaccine trial after an "unexplained illness."
Johnson & Johnson said in a statement Monday night that illnesses, accidents, and other bad results "are an expected part of any clinical study, especially large studies." And it said a group of independent safety experts, as well as its own scientists, are trying to learn the cause of the illness.
The study halt was first reported by the medical news website Stat.
Johnson & Johnson entered the third and final part, or phase, of vaccine testing on September 22. It was seeking 60,000 volunteers for its Phase 3 trial in the United States and other countries. Its vaccine candidate is a single injection treatment. The others are two shot treatments.
During Phase 3 trials, researchers look for any signs of possible side effects. The trials also judge effectiveness by studying who gets sick and who does not among patients taking part in them. People in one group get a shot of the experimental vaccine. People in another group receive an injection of an inactive substance.
Mathai Mammen is head of drug research and development at Johnson & Johnson. He told an investors' meeting Tuesday that the company informed the independent safety experts about the illness on Sunday. The experts asked for more information and the company is gathering it, he said.
Mammen added that the company does not yet know if the ill person had been given the experimental vaccine or the inactive substance.
Temporary stoppages of large medical studies are fairly common. Few are made public during the trials. The company noted that the suspension is voluntary; health officials did not order it.
The World Health Organization said recently as much as 10 percent of the world's population may have been infected with COVID-19. And Johns Hopkins University reported that more than 1 million people have died from the virus.
"Everybody is on the alert because of what happened with AstraZeneca," Dr. William Schaffner said in an email to Reuters news agency. He is a professor of infectious diseases at Vanderbilt University School of Medicine in Tennessee.
Last month, AstraZeneca, working with the University of Oxford in Britain, temporarily stopped its Phase 3 trial. The company later said a woman in the study had developed inflammation in her spine. The trial has since restarted in Britain, Brazil, India, and South Africa. But it is still on hold in the U.S.
Other vaccine candidates that have entered Phase 3 trials include ones from Moderna and Pfizer working with Germany's BioNTech. China has at least three different vaccines in Phase 3 human trials and Russia has one.
Late on Tuesday, drug-maker Eli Lilly announced that it has also temporarily stopped its COVID-linked antibody-drug trials for safety reasons. This treatment is similar to the combined antibody treatment from Regeneron given to U.S. President Donald Trump on October 2.
I'm Caty Weaver.