Late-stage studies of AstraZeneca's COVID-19 vaccine candidate, being developed by Oxford University, are on temporary hold while the firm investigates whether a recipient's "potentially unexplained" illness is a side effect of the shot. In a statement on Tuesday evening, the company said its "standard review process triggered a pause to vaccination to allow review of safety data".

AstraZeneca didn't reveal any information about the possible side effect except to call it "a potentially unexplained illness". Health news site STAT first reported the news, saying the possible side effect occurred in the UK. An AstraZeneca spokesperson confirmed the pause in vaccinations covers studies in the US, Brazil and South Africa.