RSVpreF

Moderna shares sank 11% on Wednesday after the biotech revealed 18-month efficacy data for its newly approved respiratory syncytial virus (RSV) vaccine mRESVIA (mRNA-1345). The results, presented before a panel of advisors to the US Centers for Disease Control and Prevention (CDC), showed that mRESVIA's effectiveness waned substantially compared to rival RSV vaccines from GSK and Pfizer.The CDC's Advisory Committee on Immunization Practices (ACIP) convened this week to vote on which patient groups should receive RSV, influenza, COVID-19 and other vaccines this fall.US regulators late last month approved mRESVIA – based on the same mRNA technology Moderna uses for its COVID-19 vaccine Spikevax – to protect adults 60 and older from lower respiratory tract disease (LRTD) caused by RSV infection. The shot is expected to be available in time for the start of this fall's RSV season.Efficacy dwindles to about 50%According to Moderna's ACIP presentation, mRESVIA demonstrated 50.3% efficacy at preventing RSV-related LRTD with two or more symptoms after 18 months, and 49.9% efficacy at preventing more serious infection involving at least three symptoms over the same time period. That stands in stark contrast to the vaccine's initial potency of 83.7% reported at 3.7 months in an earlier analysis.A spokesperson for Moderna offered some context, saying that "immunity from RSV is not lifelong, and as with all currently licensed RSV vaccines, mRESVIA demonstrates waning (effectiveness) over time." The biotech is banking on mRESVIA's convenience factor to differentiate it in the market, highlighting its availability in pre-filled syringes to make it easier to administer.Lagging behind rivalsStill, the longer-term data raise concerns about mRESVIA's ability to carve out its own niche in RSV while facing two competitors, both of which were approved by the FDA last year for people aged 60-plus.A single dose of GSK's Arexvy reduced symptomatic RSV LRTD by 82.6% during the first RSV season compared to placebo, and by 56.1% during the second RSV season. Meanwhile, Pfizer's Abrysvo was found to be 77.8% effective against RSV-associated LRTD with three or more symptoms through two seasons.Evercore ISI analysts suggested that "GSK's Arexvy still appears to have the most impressive VE (vaccine efficacy) of the group, which we believe will help it to maintain majority market share." Arexvy generated about $1.5 billion in sales last year, followed by Pfizer's Abrysvo at $890 million, although a recent tender win in the UK could see Pfizer's shot turn up the heat. For more, see – Spotlight On: Domestic setback for GSK's RSV vaccine could show Pfizer means business.Analysts have projected mRESVIA sales of $397 million this year, potentially reaching blockbuster status with $1.5 billion in sales by 2026.Pfizer's vaccine is also approved for maternal use to protect infants and the company is hoping to grow that to all at-risk adults aged 18 and older, while GSK's shot was recently greenlit for people ages 50 to 59 who are at high risk of severe RSV.ACIP votes to broaden RSV useMeanwhile, the CDC's ACIP panel unanimously recommended late Wednesday that RSV vaccines be given to all people ages 75 and older if they have not yet had one, as well as to those aged 60 to 74 at risk of severe disease because they have other health conditions. If the CDC director ultimately waves through the policy recommendation, that would be a step-up from previous guidance, which said that older adults may be offered a vaccine, but stopped short of saying they should be given a shot.