The families of two Black babies who died in 1967 after secretly being given an experimental vaccine are suing the United States government for damages, their lawyers said on Thursday.

The babies, Ross Otto Hambrick and Victor Marcellus King, were used to test an early vaccine against respiratory syncytial virus (RSV), a highly contagious virus, the leading cause of hospitalization among infants in the United States.

"The complaint alleges that tissue samples harvested from their autopsies decades later informed the development of RSV vaccines approved" by the federal regulators in 2023, and are "now generating billions in revenue," their attorneys said in a press release.

They allege the babies, aged two months old and four months old, were chosen without their parents' knowledge or consent to test "a dangerous, highly concentrated experimental vaccine known as 'Lot 100.'"

Both boys died in January 1967, the statement said.