After comparing the response to the two types of vaccines for the respiratory syncytial virus (RSV) based on its fusion protein (F), prefusion (pre-F) versus postfusion (post-F) vaccines, scientists at the National Institutes of Health (NIH) and Astrazeneca plc have demonstrated that targeting the pre-F protein led to better protection. No more bets on RSV immunization based on the post-F protein of the virus. Laboratories can now bet all on red for the pre-F technology.