Scientists have developed an RNA-based vaccine strategy that can effectively combat any virus strain. Rather than guessing at which virus train will be prevalent, this promises a universal and safe solution that can even be used for for infants and those with weakened immune systems. Unlike traditional vaccines, this approach uses interfering RNA (RNAi) molecules to target a common part of a virus's genome. This technology could lead to versatile one-shot vaccines against various viruses, including COVID and the flu.