When the Pfizer-BioNTech COVID-19 vaccine was authorized for emergency use by the Food and Drug Administration (FDA) in December 2020, Donald Trump referred to it as a “medical miracle.”

“This is one of the greatest scientific accomplishments in history. It will save millions of lives and soon end the pandemic once and for all,” Trump said at the time in a speech delivered from the Oval Office.

COVID-19 vaccines, made with mRNA technology, were quickly rolled out with then-Health and Human Services Secretary Alex Azar referring to the vaccine as “safe and extraordinarily effective.”

However, last week, Robert F. Kennedy Jr. announced that the government was canceling at least $500 million of federally funded mRNA vaccine development, potentially affecting U.S. preparedness for future pandemics and squashing enthusiasm for technology that has been hailed as a potential promise for cancer and HIV vaccines.