Key Differences Between FDA-Approved RSV Vaccines

Currently, 3 FDA-approved RSV vaccines are available for high-risk adults, each with unique mechanisms and formulations. Two of these are recombinant protein-based vaccines: One is adjuvanted, and the other is a bivalent vaccine targeting both RSV-A and RSV-B subtypes. The third option is an mRNA-based vaccine. All 3 target the prefusion F protein—a key structure on the surface of the RSV virus that enables it to enter human cells. The vaccines prompt the body to develop protective antibodies by presenting this protein to the immune system.

The recombinant vaccines use a lab-produced version of the prefusion F protein. The adjuvanted vaccine includes an immune-boosting agent to enhance response, whereas the bivalent version covers both main viral subgroups, offering broader protection. The mRNA vaccine, by contrast, delivers genetic instructions for the body to temporarily produce the prefusion F protein, triggering an immune response without altering the body’s DNA. It's important to clarify that mRNA vaccines do not integrate with a person’s genetic material, a common misconception fueling hesitancy.

Aside from their biological differences, these vaccines vary in preparation and administration. The 2 recombinant vaccines require reconstitution before intramuscular injection, which adds an extra preparation step for health care providers. In contrast, the mRNA vaccine comes in a ready-to-use prefilled syringe, potentially simplifying the vaccination process. Understanding these differences helps providers select the most appropriate option for their patients and address questions around efficacy, safety, and logistics. Education around the science and the delivery process is essential to improving acceptance and uptake, particularly among older adults and those managing chronic health conditions.