The U.S. Food and Drug Administration (FDA) is considering adding the strongest safety warning available to COVID-19 vaccines.

The US Food and Drug Administration intends to put a “black box” warning on Covid-19 vaccines, according to two people familiar with the agency’s plans.

The FDA intends to place a black box label—its most serious warning—on COVID-19 vaccines, according to reporting by CNN. It is unclear if the warning would apply to Moderna’s, Pfizer/BioNTech’s and Novavax’s shots,

The FDA posted its warning letters on December 12, naming Walmart, Target, Kroger, and Albertsons for failing to quickly remove ByHeart infant formula from sale after its recall on November 14. On November 20, Newsweek reported the botulism outbreak had affected 31 babies across 15 countries.

The recalled formula, ByHeart Baby Formula, has been linked to 51 cases of confirmed or suspected infant botulism.

FDA weighs black box warning for COVID-19 vaccines, signaling a major shift in safety labeling and regulatory approach for these shots.

The Food and Drug Administration has launched a safety review of two approved RSV drugs for infants, the latest immunizations to face scrutiny under Health Secretary Robert F. Kennedy Jr. No safety issues have been reported with either of the respiratory syncytial virus drugs: Beyfortus, from Sanofi and AstraZeneca, and Enflonsia, from Merck.