"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.

Adams, who served as surgeon general during the first Trump administration, said Kennedy's assertions about the efficacy of mRNA vaccines are "simply not true."

President Donald Trump hailed as a “medical miracle” the mRNA vaccines developed to combat the deadly COVID-19 pandemic in 2020. Now, his health secretary Robert F. Kennedy Jr., is effectively halting the vaccine technology’s advancement.