Final stage testing of AstraZeneca's COVID-19 vaccine has been put on hold after a test subject came down with "a potentially unexplained illness" in connection with the drug.
Although AstraZeneca officials have not released details of the vaccine's side effect, they released a statement saying their "standard review process triggered a pause to vaccination to allow review of safety data."
This vaccine is one of three in the final testing stages in the US.
The other two, Moderna and Pfizer, say their versions work differently to fend off the coronavirus than AstraZeneca's does.