Pharmaceutical giant Johnson & Johnson announced on Monday the suspension of its clinical trial of a vaccine against COVID-19 after one of the participants fell ill.
"We have temporarily paused further dosing in all our COVID-19 vaccine candidate clinical trials, including the entire Phase 3 trial, due to unexplained illness in one participant," the group said in a statement.
The company didn't reveal the nature of the person's illness. “We must respect this participant’s privacy,” the statement said.
“We’re also learning more about this participant’s illness, and it’s important to have all the facts before we share additional information.”
The company's current protocols provide for the suspension of a study to determine whether the illness, in this case, is related to the drug being evaluated and whether the trial can be resumed.
Because of the trial's suspension, recruitment for participants for phase 3 testing has also been frozen.
Recruitment of volunteers for phase 3 of the Johnson & Johnson clinical trials began at the end of September, with the aim of enrolling 60,000 participants at more than 200 sites in the United States and other countries, the group and the US National Institutes of Health (NIH) announced.
Trials were also taking place in Argentina, Brazil, Chile, Colombia, Mexico, Peru and South Africa.
Johnson & Johnson is one of four companies in advanced stages of trialling a vaccine for coronavirus and was due to publish its results early next year.
The United States granted some $1.45 billion (€1.2 billion) in financing to the company as part of Operation Warp Speed, the White House's initiative to speed up the development and production of a viable COVID-19 vaccine.
Its candidate vaccine is based on a single dose of an adenovirus, which is responsible for the common cold and has been modified so that it cannot replicate, combined with a part of the Sars-CoV-2 coronavirus called the spike protein (or "spike") that it uses to penetrate human cells.
Johnson & Johnson used the same technique for its Ebola haemorrhagic fever vaccine, which was approved for marketing by the European Commission in July.
Pausing clinical trials because of illness is not uncommon.
In September, trials of the COVID-19 candidate vaccine developed by AstraZeneca and Oxford University, considered one of the most promising, were also halted after a UK participant developed an unexplained pathology.
The trials resumed in the UK and Japan in early October but haven't yet restarted in the United States.