‘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 company said.

The participant’s illness is being reviewed and evaluated under company guidelines.

‘Adverse events – illnesses, accidents, etc. – even those that are serious, are an expected part of any clinical study, especially large studies,’ the statement said.

‘We must respect this participant’s privacy. We’re also learning more about this participant’s illness, and it’s important to have all the facts before we share additional information.’

Some 60,000 people in three continents were taking part in the trials for the one-dose vaccine.

EU buy

Last week, the European Commission signed a contract with Janssen for the supply of 200 million doses of its coronavirus vaccine. Health minister Hugo de Jonge said at the time the vaccine, if successful, is likely to become available in the second quarter of 2021.

In September, AstraZeneca has paused global trials of its experimental coronavirus vaccine after an unexplained illness in a participant but they resumed three days later.