The targeting of the vaccine technology once considered revolutionary follows intense criticism by conservatives and anti-vaccine activists.

The US Department of Health and Human Services (HHS) plans to cancel $500m (£376m) in funding for mRNA vaccines being developed to counter viruses like the flu and Covid-19. The move will impact 22 projects being led by major pharmaceutical companies, including Pfizer and Moderna, for vaccines against bird flu and other viruses, HHS said.