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."

The US Department of Health and Human Services (HHS) plans to cancel $500m (£376m) in funding for mRNA vaccines being developed to counter viruses that cause diseases such as the flu and Covid-19.

Although mRNA vaccines saved millions of lives during the COVID-19 pandemic, U.S. Health Secretary Robert F. Kennedy Jr. incorrectly argued they are ineffective to justify the Department of Health and Human Service's recent decision to cancel $500 million in government-funded research projects to develop new vaccines using the technology.