The U.S. Department of Health and Human Services said on 5 August it will wind down government support for messenger-RNA vaccines, cancelling 22 Biomedical Advanced Research and Development Authority contracts and solicitations valued at about $500 million. The decision freezes late-stage work on several respiratory-virus shots, including Moderna’s H5N1 bird-flu candidate, and rejects pending proposals from Pfizer, Sanofi, CSL Seqirus, Gritstone and others. Health Secretary Robert F. Kennedy Jr. said a post-pandemic review showed mRNA vaccines “fail to protect effectively against upper respiratory infections like COVID and flu.” He added that the money will be shifted to whole-virus and other platforms the agency considers “safer” and more durable as viruses mutate. The announcement triggered sharp criticism from scientific and medical leaders. Michael Osterholm, who directs the Center for Infectious Disease Research and Policy, called the step “the most dangerous public-health decision I have seen in 50 years.” The American Medical Association, Nobel laureate Katalin Karikó and other experts warned the retreat could slow development of vaccines for future pandemics as well as for cancer and HIV, undermining a technology credited with saving millions of lives. The reversal also challenges one of President Donald Trump’s signature achievements—Operation Warp Speed—and unsettled biotech investors, with Moderna shares slipping after the news. White House officials said Trump will meet with Kennedy to review the policy as industry groups and lawmakers press for restoration of funding for the rapid-response platform.