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. The longtime vaccine critic said in an X video posted Tuesday evening that mRNA vaccines do not adequately prevent upper respiratory infections such as COVID-19 and the flu, advocating instead for the development vaccines that use other processes. COVID-19 is the only virus for which real-world data on mRNA vaccine effectiveness is currently available, as mRNA vaccines for other diseases, including the flu, are still under development.