Had an interesting question from a friend today about the new RSV vaccines - whether they will make RSV infection rare, or just reduce RSV severity.
It is too early to tell on that front, but preliminary data from challenge trials is promising that these vaccines could potentially reduce infection and transmission risk too.
Most of the RSV vaccines being investigated target the F protein, which is highly conserved across RSV strains, so hopefully that will mean the immune response will be durable amidst viral mutation. With influenza virus, infection and vaccination actually do produce durable immune responses to the specific strain, but the virus mutates so rapidly and significantly on areas the immune system targets that protection rapidly wanes. In contrast, with RSV the issue is that RSV infection doesn't produce a durable immune response to begin with, such that repeat infections occur throughout our lives.
I wanted to highlight that these RSV vaccines use the prefusion F protein. Stabilizing the coronavirus spike protein was a key part of the development of the coronavirus vaccines. Both vaccines owe themselves to this breakthrough in protein conformation stabilization thanks to the work of NIH scientists Jason McLellan and Barney Graham on RSV, MERS, and subsequently SARS-COV-2. One issue with the early failed RSV vaccines is that they displayed postfusion F proteins, which unfortunately led to disease enhancement in vaccinated individuals. This has not been seen in the coronavirus vaccines or the new RSV vaccines thankfully.