The F protein (Glycoprotein F) on the surface of RSV is a major protective antigen essential for viral attachment and entry. During the fusion of the virus with the host cell membrane, the F protein undergoes a conformational change from the prefusion (Pre-F) to the postfusion (Post-F) state. Studies have shown that the Pre-F conformation can induce more effective neutralizing antibodies, providing a key clue to overcoming the ERD (enhanced respiratory disease) reactions observed with inactivated vaccines. Therefore, research based on the Pre-F protein conformation has become a significant direction in RSV vaccine development, and all currently approved RSV vaccines are recombinant protein subunit vaccines based on the Pre-F conformation. The RSV-post F0 protein typically refers to the stabilized form of the Respiratory Syncytial Virus (RSV) F protein after it has undergone structural rearrangement from its prefusion (Pre-F) conformation to its postfusion (Post-F) conformation during the fusion process with the host cell membrane. Although early vaccine candidates based on the Post-F protein were able to induce neutralizing antibodies, the titers of these antibodies were often too low to effectively protect against RSV infection.