I think it will be 2B or so - consensus is for 1B
I also think GSK will garner the majority of sales
the rate of upper resp infection is just under .4% in vaccinated older adults versus 1.4% in unvaccinated, so if the vaccine gets to 7M older adults (above consensus which is 4M or so), it will reduce the number of outpatient visits in older adults w RSV from around 100K to 28K. There are still about 80M older adults that won't be getting the vaccine
Doing the math in peds is a bit trickier - infections in peds will go down w beyfortus especially in the first year, but the effect may be a bit more muted as kids over 1-2yo who got beyfortus at birth/early infancy will likely have more severe infection w RSV when they first contract the virus at a slightly older age. I posted numbers in peds post beyfortus on this board previously
Bottom line is that vaccines will lower activity of RSV overall very modestly, and a normal RSV season will yield plenty of patients still to enroll in the studies, and the market for an antiviral will remain pretty high IMO (especially now that PFE has essentially dropped out of the race)
as you know the covid drug is aimed at outpatients not at hospitalized patients, so the link between covid hospitalizations and the target market for 235 is more tenuous - looking at numbers of outpt infections is going to more closely track the use of drugs like paxlovid, although a more severe variant that causes more hospitalizations would increase outpateint use of these drugs somewhat
