Johnson & Johnson suspended its Covid vaccine study to investigate why a study participant got sick.
The company said an independent review would look to see if the person’s unexplained symptoms are related to the bump.
As a precautionary measure, recruitment for the phase 3 study has been suspended.
In large studies with tens of thousands of volunteers, it was expected that some might become unwell during the study period.
The company said that for privacy reasons it could not provide any details about the participant.
“We also learn more about this participant’s illness and it is important to know all the facts before sharing additional information,” said a statement.
It’s not the first Covid vaccine study to be suspended – a participant in the Oxford University UK study also had an unexplained disease, but resumption has since been considered safe, except in the US, where regulators are still discussing with manufacturer Astra Zeneca.
Nearly 180 vaccine candidates are being tested worldwide, but none have completed clinical trials.
The Johnson & Johnson Jab, like the Astra Zeneca at Oxford University, is in the advanced test stage.
Both use a modified cold virus to prepare the immune system against Covid.
The Johnson & Johnson study began recruiting participants in late September with the aim of enrolling up to 60,000 volunteers in more than 200 locations in the United States, as well as South America and South Africa.