Moderna's stock falls after data shows biotech's RSV vaccine trails rivals after 18 months

By Ciara Linnane

Moderna's second approved product appears less effective than shots from GSK and Pfizer over time

Moderna Inc.'s stock fell 9% Wednesday, after the company said that its respiratory syncytial virus, or RSV, shot showed 50% efficacy in preventing the illness after 18 months.

The vaccine, called mResvia, showed about 81% efficacy in a primary analysis at 3.7 months.

GSK's vaccine, Arexvy, was 68% effective over 23.3 months in a clinical trial; and Pfizer Inc.'s Abrysvo was 78% effective after 16.4 months.

Moderna made the disclosure in a presentation to the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices, or ACIP, which will vote later Wednesday on which patient groups should get RSV, flu, COVID-19 and other vaccines in the fall.

An expansion to add those aged 50 to 59 to the current recommendation for adults aged 60 and older would add millions of patients to the program.

The CDC is not obliged to follow the recommendations of the ACIP, although it often does.

The Food and Drug Administration approved mResvia in May as a treatment for adults aged 60 and older, introducing fresh competition for the RSV vaccines developed by GSK (GSK) (UK:GSK) and Pfizer (PFE).

It was Moderna's second approved product after its COVID-19 vaccine Spikevax, which has seen sales fall sharply as the world has come out of the pandemic.

The shot is expected to be available in time for the start of this fall's RSV season, Moderna said.

Moderna is aiming to differentiate its RSV shot from the competition by offering single-dose, pre-filled syringes, which it says will save time and cut the risk of errors in administering the vaccine.

GSK's shot dominated sales of RSV vaccines last year, chalking up $1.5 billion of sales after it became the first to win U.S. approval.

"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," Evercore ISI analysts said Wednesday.

Evercore has an in-line rating on Moderna's stock.

RSV often causes mild, cold-like symptoms, but can be severe, particularly for infants and older adults. About 60,000 to 160,000 people age 65 and older are hospitalized each year due to RSV, according to the Centers for Disease Control and Prevention.

Moderna's stock was on track for its biggest one-day percentage decline since Dec. 27 of 2022, when it fell 9.5%. The stock is down 12.6% in the month to date, but is still up 25% in the year to date.

The SPDR S&P Biotech ETF XBI has gained 3.6% in the same time frame and the S&P 500 SPX has gained 14.7%.

-Ciara Linnane

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06-26-24 1421ET

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