The US Food and Drug Administration (FDA) apparently wants to introduce the highest warning label for coronavirus vaccines. This is the so-called “black box,” a black-framed text that could also warn of fatal consequences. CNN reports this, citing two sources familiar with the matter.

The text box is to be placed before the prescribing information and will indicate physical limitations or even fatal illnesses that may occur in response to vaccination. This information is intended to help weigh the positive effects of the vaccines.

This is currently common practice on the packaging of opioids. These painkillers currently carry warnings about abuse, addiction, and even death. Other pharmaceutical products have also carried warnings about their side effects, most recently a vaccine against monkeypox, which can cause heart muscle inflammation. However, the Trump administration's new initiative covers an entire group of drugs.

It is not yet clear whether the warning will be printed on all COVID vaccines or whether only mRNA preparations will be affected. Three vaccines against the virus are currently approved in the US, with the Pfizer and Moderna products both based on mRNA technology. It is also unclear whether the warnings will apply to all age groups. The plans are not yet finalized, but could be presented by the end of the year, according to CNN.